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BOOK    6  12.82.B29   c.  1 

BASTIAN    f    BRAIN    AS    ORGAN   OF    MIND 


3  T153  Q0D3S154  b 


This  Book  may  be  kept  out 


I^^Y3t^92i 


E 
1 


THE    BRAIN 


AS 


AN    ORGAN    OF    MIND 


BY 

H.  CHARLTON   BASTIAN,  M.A.,  M.D,  F.R.S. 

PROFESSOR   OF    PATHOLO'JJCAL   ANATOMY,    AND   OF   CLINICAL   MEDICINE 

IN     UNIVERSITY    COLLEGE,    LONDON  ;     PHYSICIAN    TO     UNIVERSITY    COLLEGE     HOSPITAL 

AND  TO  THE   NATIONAL  HOSPITAL  FOR  THE   PARALYZED  AND   EPILEPTIC 


WITH  ONE  HUNDRED  AND  EIGHTY-FOUR  ILLUSTRATIONS 


NEW  YORK: 
D.  APPLETON  AND  COMPANY, 

72     FIFTH     AVENUE. 
1896 


IC.^^. 


CONTENTS. 


CHAPTER  I. 

FAGB 

The  Uses  and  Origin  of  a  Nervous  System      .        .       #        I 


CHAPTER  11. 

The    Structure    of  a  Nervous   System — Nerve  Fibres, 

Cells,  and  Ganglia 26 


CHAPTER  III. 
The  Use  and  Nature  of  Sense  Organs     ....      55 

CHAPTER  ly. 
The  Nervous  System  of  Mollusks 70 

CHAPTER  y. 
The  Nervous  System  op  yERMEs 86 

CHAPTER  yi. 
The  Nervous  Syspem  of  Arthropods 93 

CHAPTER  yil. 

Data  concerning  the  Brain  derived  from  the  Study  of 

THE  Nervous  System  of  Invertebrates       .        .        .    107 


iV  CONTENTS. 


CHAPTER  YIII. 

PAGE 

The  Brain  of  Fishes  and  of  Amphibia      .        •        •        •    111 


CHAPTER  IX. 
The  Brain  of  Reptiles  and  of  Birds.        «        •        •        •    125 

CHAPTER  X. 
The  Scope  of  Mind •        •        •    138 

CHAPTER  XL 
Reflex  Action  and  Unconscious  Cognition.       ,        •        •    156 

CHAPTER  XXL 
Sensation,  Ideation,  and  Perception  .        •        •        •        .    lt)8 

CHAPTER  XIII. 
Consciousness  in  lower  Animals 195 

CHAPTER  XIV. 
Instinct:  its  Nature  and  Origin        .        •        #        •        .    220 

CHAPTER  XV. 

Nascent  Reason,  Emotion,  Imagination  and  Volition       .    23G 

CHART  I^]R  XVI. 
The  Brain  of  Quadrupeds  and  some  other  Mammals       .    25'lf 

CHAPTER  XVII. 
The  Brain  of  Quadrumana 286 


CONTENTS. 


CHAPTER  XVIII. 
The  Mental  Capacities  and  Powers  of  Higher  Brutes  .    307 


CHAPTER  XIX. 
Development  of  the  Human  Brain  during  Uterine  Life    332 

CHAPTER  XX. 

The  Size  and  Weight  of  the  Human  Brain     .        •        •    347 

CHAPTER  XXL 
The  External  Configuration  of  the  Human  Brain.        .    37S 

CHAPTER  XXII. 
From  Brute  to  Human  Intelligence  .        •        •        •        •    411 

CHAPTER  XXIII. 
The  Internal  Structure  op  the  Human  Brain        •        •    428 

CHAPTER    XXIV. 

The   Functional   Relations   of   the  Principal  Parts   op 

THE  Brain ^"17 

CHAPTER  XXV. 

PHRKNCLOGY:    OlD    AND    NeW •      611 

CHAPTER  XXVL 
Will  and  Voluntary  Movements         .        .        •        •  ^     .    548 


Vi  CONTENTS. 


CHAPTER  XXYII. 

PAGE 

Cerebral  Mental  Substrata        ...•••    689 


CHAPTER  XXYIII. 

Speaking,   Reading,    and    Writing:    as   Mental   and    as 

Physiological  Processes 601 


CHAPTER  XXIX. 

The  Cerebral  Relations  of  Speech  and  Thought    .        ,    613 


CHAPTER  XXX. 

Further   Problems   in   regard   to   the    Localization   of 

Higher  Cerebral  Functions 673 


APPENDIX. 

Views    concerning    the    Existence    and    Nature    of   a 

Muscular  Sense 691 


LIST    OF    WOODCUTS. 


FTG.  IPAGB 

1.  Different  kinds  of  Nerve  Cells 22 

2.  Small  Sympathetic  Ganglion  (Human)  with  Multipolar  Cells.    (Leyclig)         .  27 

3.  Human  Nerve  Fibres.    (Kolliker) 31 

4.  Small  Branch  of  a  Muscular  Nerve  of  the  Frog,  near  its  termination,  show- 

ing divisions  of  the  Fibres     (Kolliker) 32 

5.  Gelatinous  Nerve  Fibres  from  the  Calf.    (Henle) 33 

6.  Portion  of  the  Trunk  of  a  Nerve.     (Quain  after  Bell) 34 

7.  Cervical  Plexus.    (Sappey  after  Hirschfeld) 35 

8.  Ganglion  Cell  from  anterior  Horn  of  Grey  Matter  in  the  Spinal  Cord.    (Max 

Schultze) 36 

9.  Portion  of  Neuroglia  from  the  Spinal  Cord.    (Kolliker) 39 

10.  Three  bipolar  Ganglion  Cells  from  the  fifth  nerve  of  the  Pike.     (Strieker)    .  41 

11.  Three  bipolar  Ganglion  Cells  from  the  auditory  nerve  of  the  Pike.    (Sti'icker)  41 

12.  Division  of  a  very  slender  Nerve  Fibre  and  its  communication  with  a  plexus 

of  fibrils.     (Gerlach) 42 

13.  Multipolar  Ganglion  Cell  from  anterior  grey  matter  of  the  Spinal  Cord  of  an 

Ox.     (Deiters) 43 

14.  Motor  Nerve  Cells  connected  by  intercellular  processes.     (Vogt)     ...  45 

15.  '  Sympathetic  '  Ganglion  Cell  of  a  Frog.     (Quain  after  Beale)  .        .        .        .40 

16.  Multipolar  Ganglion  Cells  from  '  Sympathetic  '  of  Man.     (Max  Schultze)       .  47 

17.  Nervous  System  of  one  of  the  Eolidse.    (Gegenbauer) 49 

18.  Nervous  System  of  the  Great  Green  Grasshopper.     (Newport)         ...  61 

19.  Transverse  Section  through  Human  Spinal  Cord.    (Sappey  after  Stilling)     .  52 

20.  General  View  of  Nervous  System  of  Man.    (Mivart) 53 

21.  Nervous  System  of  an  Ascidian.    (Solly  after  Cuvier) 71 

22.  „              „           an  Oyster.    (Todd) 73 

23.  „              „           the  Common  Mussel.    (Owen) 74 

24.  „              „           the  Common  limpet.    (Todd) 78 

25.  ,,              „           a  Chiton.    (Garner) 79 

26.  Head  and  Nervous  System  of  the  Common  Garden  Snail.    (Owen)       ,        .  80 

27.  Nervous  System  of  the  Common  Slug.     (Solly  after  Baly)        ....  81 

28.  ,,             ,,           ,,       Pearly  Nautilus.    (Gegenbauer  after  Owen       .        ,  82 

29.  „              „            „       Common  Cuttlefish.     (Uwen) 83 

30.  Head  and  Brain  of  a  Nemertean.    (After  Mcintosh) 88 

31.  Nervous  System  of  the  Medicinal  Leech.     (Owen) 89 

32.  „               „           a  Serpula.    (Gegenbauer  after  Quatrefages)      ...  91 

33.  Anterior  part  of  the  Nervous  System  of  an  lulus.    (Owen)     ....  94 

34.  Nervous  System  of  a  Common  Saudhopper.    (Grant)       .       .       •       •       .  86 


Viil  LIST    OF   WOODCUTS. 

FIG.  PAGE 

35.  Nervous  System  of  Cymothoa.    (Grant)     .        .        .••••.  96 

30.        „                „           a  Crab.     (Milne  Edwards) 97 

37.  Head  and  Nervous  System  of  a  Spider.    (Owen  after  Duges)  ....  99 

38.  Nervous    System  of    a   great   Scorpion -like    Spider.      (Gegeubauer   after 

Blanchard) 100 

89.        ,,  „  fiJl-grown  Caterpillar  of  Privet-Hawk-Moth.   (Solly  after 

Newport) 102 

40.  „               „           the  Privet-Hawk-Moth  in  Chrysalis  Stage.    (Solly  after 
Newport) 102 

41.  ,,  ,,  the  perfect  Insect.    (Solly  after  Newport)         .        .        .102 

42.  Brain  and  adjacent  parts  of  Nervous  System  of  a  Beetle.    (Newport)    .        .  103 

43.  Nervous  System  of  a  "White  Ant.    (Gegenbauer  after  Lespfes) .        .        .        .  105 

44.  ,,             ,,         „     Water  Beetle.    (Gegenbauer) 105 

45.  „             ,,         ,,     Fly.    (Gegenbauer  after  Blanchard)       ....  105 

46.  Brain  and  Cranial  Nerves  of   the   Perch,  side  view.      (Gegenbauer  after 

Cuvier) 113 

47.  Brain  of  the  Pike.    (Solly; 114 

48.  ,,          „      Shark,  side  view.    (Owen) 115 

49.  „          „       Roach.     (After  Spurzheim) 115 

50.  „  „      Perch,  upper  Surface.     (Owen  after  Cuvier)         .        ,        .        .116 

51.  „          „         ,,        under  Surface.     (Owen  after  Cuvier)         ....  116 

52.  „          „      Carp.     (Ferrier) 117 

53.  „          „      Ray  or  Skate,  upper  aspect.    (Mivart) 117 

54.  „          „      Gar-Pike.    (Owen) 118 

65.       „          „      Whiting.     (SoUy) 118 

56.  Brain  and  Spinal  Cord  of  the  Frog.    (Solly) 119 

57.  Brain  of  the  Cod,  under  surface.    (Owen) 122 

58.  Brain  and  Cranial  Nerves  of  Boa  Constrictor.    (Rymer  Jones  after  Swan)     .  1 26 

59.  Brain  of  Lizard.     (Owen) 127 

60.  „        the  Perch,  vertical  longitudinal  section  of.     (Mivart)         .        .        .128 
CI.          „        Tvirtle,  side  view.     (Solly) 129 

62.  ,,        Pigeon.     (Ferrier) 131 

63.  Brain  and  part  of   Spinal  Cord  of  Chick  sixteen  days   old.     (Owen  after 

Anderson) 131 

64.  ,,               ,,                      ,,                      „      twenty  days  old.     (Owen  after 
Anderson) 131 

65.  Brain  of  Common  Fowl.    (Spurzheim) 133 

66.  ,,        Pigeon,  side  view.     (Mivart) 133 

67.  ,,        Sea  Gull.     (Owen  after  Atiderson)        .        .        .        .        .        ,        .  134 

68.  Brain  and  Spinal  Cord  of  Kangaroo.     (( )wen) 2;".5 

69.  I irain  of  the  Horse,  outer  surface.    (S  Uy  after  Lcurct) 250 

70.  „        Agouti.     (Owen) 257 

71.  „        Beaver.     (Owen) 257 

72.  „        Horse,  inner  surface.     (Solly  after  Leuret) 258 

73.  „        Rabbit,  under  surface.     (Solly  after  Lcurct) 2(il 

74.  „        Dolpliin,  under  surface.     (Owen  after  Tiedomanu)    ....  2ii2 

75.  „        Horse,  upper  aspect.     (Owen) 203 

76.  „        Hare,  upper  aspect.     (Spurzheim) 203 

77.  „        Porpoise.     (Solly) 204 

78.  ,,        Bat,  side  view.    (Solly) .  205 

79.  Cerebellum  of  the  Cat.     (Ferrier) 205 

:J0.            ,,              ,,        Dog.     (Ferrier) 205 

81.  Brain  of  the  Squirrel,  dissected.    (Solly) 206 


LIST    OF    WOODCUTS.  ix 

»IO.  PXGB 

82.  Head  and  Brain  of  a  Squirrel,  side  view.     (Solly)  ......  267 

83.  Brain  of  a  Chelonian.    (Gegenbauer)         ....••..  268 

84.  „      „    Foetal  Calf.    (Gegenbauer) 268 

85.  „      ,,    Cat.    (Gegenbauer) 268 

86.  „         the  Dolphin,  dissected.    (Owen  after  Tiedemann)    ....  269 

87.  „        „      Dog,  dissected.     (Ferrier) 270 

88.  „        ,,       Rock  Coney.     (Owen) 280 

89.  Left  Cerebral  Hemisphere  of  the  Horse.    (Owen)   ..,,..  280 

90.  „                       „                „        Rhinoceros.     (Owen) 280 

91.  „                      „               „       Stag.     (Owen) 280 

92.  „                       „                „        Giraflfe.    (Owen) 280 

93.  Brain  of  the  Rock  Coney,  side  view.    (Owen) 281 

94.  „          „      Giraffe,  side  view.    (Owen) 281 

95.  Right  Cerebral  Hemisphere  of  the  Elephant,    (Owen) 282 

96.  Brain  of  the  Cat.    (Tiedemann) 283 

97.  „          „      Dog.     (Tiedemann) 283 

98.  „          „      Coati.     (Owen) 2S3 

99.  „          „      Cat,  side  view.    (Owen) 283 

iOO.      „          „      Fox.     (Owen) 283 

101.  ,;          „      Dolphin,  upper  aspect.    (Owen  after  Tiedemann)     .        .        .  284 

102.  „          „      Brown  Macaque 287 

103.  „          „      Aye-aye.    (Owen) 289 

104.  „          „      Marmoset.     (Owen) 289 

105.  „          „      Squirrel-Monkey.     (Owen) 2e.9 

106.  „          „      Macaque.    (Owen) 289 

107.  „          ,,       Gibbon.     (Owen) 289 

108.  „           a  fifth  month  Human  Fcetus.  (Owen) 289 

109.  „           the  Howler  Monkey.    (Duncan) 290 

110.  „          „       Mangabey,  upper  aspect.     (Vogt) 291 

111.  „          „                „         side  view.     (Vogt) 292 

112.  ,,          „      Wanderoo,  upper  aspect,    (^^ogt) 293 

113.  „          „                ,,        side  view.    (Vogt) 293 

114.  „          „      Baboon,  upper  aspect.     (Vrolik  after  Leuret)     ....  294 

115.  „          „      Chimpanzee.    (Vogt  after  Marshall) 296 

1'6..      „          „      a  Human  Idiot.    (Vogt  after  Thcile) 297 

117.  ,,  „      Gorilla,  side  view.    (After  Bolau  and  Pansch)   .        ,        .        .298 

118.  „          „      Orang,  base  of.    (Owen  after  Tiedemann) 299 

119.  „          „           „        upper  aspect.    (Duncan) 300 

120.  ,,          ,,      Gorilla,  inner  aspect.    (Bolau  and  Pansch)         ....  301 

121.  „          „      Orang,  side  view.    (Vogt  after  Gratiolet) 302 

122.  Diagrams  illustrating  the  Progressive  Changes  in  Foetal  Brain.    (Mivart)    .  334 

123.  Sketches  of  the  Early  Form  of  the  Cerebro-Spinal  Axis  of  the  Human 

Embryo.    (Sharpey  after  Tiedemann) 336 

124.  Vertical  Section  of  the  Brain  of  a  Human  Embryo  of  fourteen  weeks. 

(Sharpey  after  Reichert) 337 

125.  Brain  and  Spinal  Cord  of  a  Foetus  of  four  months.    (Shari)ey  after  K61- 

liker) 338 

126.  Brain  of  Human  Fcetus  of  fourth  month.    (Owen) 339 

127.  „        Turtle.     (Owen) 340 

128.  The    outer  aspect  of   the  Foetal  Brain  at  six  months.     (Sharpey  after 

R.  Wagner) 341 

29.  The    upper  aspect  of    the  Foetal  Brain  at  six  months.    (Sharpey  after 

R.  Wagner) 342 


X  LIST    OF    WOODCUTS. 

no.  PAoa 

130.  The  inner  aspect  of  the  right  half   of  the  Foetal  Brain  at  six  months. 

(Sharpey  after  Reich ert) 343 

131.  Dura  Mater  with  its  vessels  enveloping  the  Brain.    (After  Hirschfeld)         .  348 

132.  Human  Cerebrum  and  Cerebellum,  side  view.     (After  Hirschfeld)        .        .  349 

133.  Brain  of  the  Hottentot  Venus,  side  view.    (Vogt  after  Gratiolet)  .        .        .  377 

134.  „                   ,,                  ,,        upper  aspect.    (Vogt  after  Gratiolet)    .        .  378 
IS"^.        ,,         a  Bushwoman,  upper  aspect.     (Heath  after  Marshall)     .        .        .  380 

136.  ,,                    „               lateral  aspect.     (Heath  after  Marshall)    .        .        .  381 

137.  Right  Cerebral  Hemisphere  of  a  Scotchman,  outer  aspect.     (Turner)  .        .  382 

138.  Upper  aspect  of  the  Brain  of  a  Scotchman.    (Turner) 383 

139.  Inner  Face  and  Tentorial  Surface  of  the  Left  Cerebral  Hemisphere.     (Tur- 

ner)     384 

140.  View  of  the  Orbital  Lobule  and  of  the  Island  of  Reil.    (Turner)          .        .  385 

141.  Brain  of  Grauss,  the  celebrated  Mathematician   and  Astronomer,  upper 

aspect.     (Sharpey  after  R.  Wagner) 387 

142.  Brain  of  Gauss,  side  view.    (Vogt  after  R.  Wagner) 389 

143.  Brain  of  a  Journalist,  front  view  of  the  Frontal  Lobes 391 

144.  Under  surface  of  the  Human  Brain.     (Allen  Thomson) 397 

145.  Under  surface  of  Cerebral  Peduncles,  Pons,  and  Medulla.    (Sappey  after 

Hirschfeld) •   .  398 

146.  Section  through  the  left  Occipital  Lobe  of  a  Human  Brain    ....  399 

147.  View  of  Occipital  Lobes  and  of  Cerebellum  from  behind,  showing  the  Occi- 

pital Groove 402 

148.  Posterior  diagrammatic  view  of  Dura  Mater  with  great  Venous  Sinuses. 

(Todd) 403 

149.  Upper  surface  of  the  Cerebellum.    (Sappey  after  Hirschfeld)        .        .        .405 

150.  Inferior  surface  of  the  Cerebellum.     (Sappey  after  Hirschfeld)    .        .        .  406 

151.  The  Lateral  Ventricles  and  their  Cornua, with  Contiguous  Structures.  (After 

Sharpey) 430 

152.  Third  and  Fourth  Ventricles  of  the  Brain  exposed.     (After  Sharpey)   .        .  431 

153.  Longitudinal  Vertical  Section  through  the  Left  Hemisphere,  showing  the 

Lateral  Ventricle  and  its  three  Cornua.     (Sappey  after  Hirschfeld)  .        .  432 

154.  Decussation  of  the  Motor  Fibres  in  the  Medulla  and  Pons.    (Broadbent)     .  434 

155.  Under  surface  of  Brain,  dissected.     (Bi'oadbent) 435 

156.  Central  Ganglia  of  the  Brain,  together  with  the  Cerebellum  and  its  Supe- 

rior Peduncles.     (^Sappey  after  Hirschfeld) 437 

157.  Transverse  Section  of  the  Cerebrum,  showing  course  of  certain  Fibres. 

(Broadbent) 439 

158.  Transverse  Section  through  the  anterior  part  of  the  left  Frontal  Lobe .        .  445 

159.  Section  through  the  third  Frontal  Convolution  of   Man.      (Ferrier  after 

Mcynert) 446 

160.  Large  Pyramidal  Cell  with  its  processes,  a  so-called 'Giant-Cell.'   (Charcot)  447 

161.  Section  of  the  Involuted  Layer  of  the  Hippocampus.     (Mejmert)          .        .  450 

162.  Longitudinal  Section  through  the  centre  of  the  Brain,  showing  the  inner 

face  of  Left  Cerebral  Heniisphere.     (Sappey  after  Hirschfeld)   .        .        .  452 

163.  Horizontal  Section  through  the  Cranium  and  the  Cerebral  Hemisiiheres, 

showing  the  '  Centrum  ovale.'    (Sappey  after  Vicq  d'x\zjT)        .        .        .  454 

164.  Horizontal  Section  through  the  Cerebrum  at  a  deeper  level,  showing  the 

Third  Ventricle  and  its  Commissures.     (Sappey) 456 

165.  The  Ujiper  Peduncles  of  the  Ccrel)cllum,  with  the  Fourth  Ventricle  and 

contiguous  parts.     (Sai)pcy  after  Hirschfeld) 4'il 

166.  The  Middle  Corel lellar  Peduncles  and  Pons,  with contigvousixirts.    (Sap^Miy 

alter  Hirschfeld) 483 


LIST    OF    WOODCUTS.  XI 

fxo.  page: 

167.  Section  of  the  Grey  Matter  of  the  Cerebellum.    (Sharpey  aft^sr  Sitnk'^y)      .    406 

168.  Part  of  the  Base  of  the  Brain  to  which  the  Cranial  Nerves  are  .*tt?'jhed, 

(Ferrier  after  Allen  Thomson) 47 1 

169.  Left  Pneumogastric  Nerve,  with  Cervical  and  Thoracic  Porti'-ns  'yt  tbc  Great 

Sympathetic.     (Jamin  after  Hirschfeld) 473 

170.  One  of  the  Sympathetic  Ganglia  from  the  right  Lateral  'Jo^Ji  o*"  the  Rabbit. 

(Owen  after  KoUiker) 475 

171.  Transverse  section  through  the  Cerebrum  of  a  Dog,  p'aov,  ing  the  posterior 

portion  of  the 'internal  capsule.'    (Charcot  after  Duret)    ....  489 

172.  Left  Hemisphere  of  the  Brain  of  a  Monkey.     (Ferrier) 5J0 

173.  Internal  aspect  of  the  right  Cerebral  Hemisphere  of  a  Monkey.   (Ferrier)    .  531 

174.  Brain  of   Monkey,  showing  a  shaded   area  corresponding  with  so-caller" 

Visual  Centre  in  the  Cortex  of  the  left  Cerebral  Hemisphere.     (Ferrier)  .     bin 

175.  Brain  of  Monkey,  showing  a  shaded  area  corresponding  with  the  so-callea 

'Auditory  Centre'  in  the  Cortex  of   the  right  Cerebral  Hemisphere 
(Ferrier) 53i 

176.  Brain  of  Monkey,  showing  shaded  area  in  Temporal  Lobe,  the  destruction 

of  which  is  said  to  caiise  loss  of  SmeU  and  loss  of  Taste.    (Ferrier)         .    507 

177.  Internal  aspect  of  the  right  Hemisphere  of  the  Brain  of  a  Monkey,  show- 

ing a  darkly  shaded  area  corresponding  with  the  so-called '  Tactile  Centre.' 
(Ferrier) 539 

178.  Groups  of  Cells  in  connection  with  the  Anterior  Roots  of  the  Spinal  Nerves 

in  Spinal  Cord  of  a  Sheep.    (Flint  after  Dean) 559 

179.  Nerve  Cell  with  many  branches,  from  one  of  Anterior  C^^mua  of  a  Human 

Spinal  Cord.    (Max  Schultze) 565 

180.  Transverse  Section  of  the  Brain  of  a  Dog,  showing  t]  .e  mterior  part  of  the 

'internal capsule.'    (Carville  and  Duret) 566 

181.  Lateral  view  of  the  Brain  of  a  Monkey,  showing  the  boundaries  of  the  so- 

called  '  motor  area '  of  the  right  Cerebral  Hemisphr.re.     (Ferrier)    .        .     571 

182.  Lateral  aspect  of  a  Monkey's  Brain,  showing  the  relative  positions  of  the 

so-called  '  Motor  Centres '  in  the  left  Cerebral  Hemisphere.     (Ferrier)      .     573 

183.  Upper  aspect  of  Monkey's  Brain,  showing  the  relalive  positions  of  some  of 

the  so-called  '  Motor  Centres '  in  the  left  Cerebral  Hemisphere.    (Ferriti)    574 

184.  Brain  of  a  Woman  who  suffered  from  Aphasia,  showing  the  traces  of  a 

lesion  in  the  posterior  part  of  the  'third  Frontal  Convolution.'  (Prevost)    676 


\*  The  Writer  desires  to  acknowledge  his  obligation  to  various  publishers 
and  authors  for  the  right  that  has  been  courteously  granted  him  to  introduce 
a  number  of  the  illustrations  which  appear  in  this  volume. 

Messrs.  Longmans  and  Co.  have  been  good  enough  to  supply  him  with 
electros  from  Quain's  "Elements  of  Anatomy,"  Solly  on  "The  Human 
Brain,"  Owen's  "Anatomy  of  Vertebrates,"  and  "The  Cyclopsedia  of 
Anatomy  and  Physiology." 

Messrs.  Mncmillan  and  Co.,  Messrs.  Smith,  Elder  and  Co.,  the  Council  of 
the  Anthropological  Institute,  and  various  authors,  both  at  home  and  abroad, 
have  also  placed  him  under  similar  obligation. 


THE 


BRAIN  AS  AN  ORGAN  OF  MIND. 


CHAPTER    I. 

THE    USES   AND    ORIGIN    OF    A   NERVOUS    SYSTEM. 

A  LIFELESS  object  makes  no  appreciable  response  to  ex- 
ternal impressions.  If  we  touch  a  rock  or  a  stone,  no 
answering  movements  follow.  Day  and  night,  summer 
and  winter  succeed  one  another,  and  yet,  though  inaui- 
mate  objects  undergo  imperceptible  molecular  changes, 
they  yield  no  active  and  visible  response  either  to  diurnal 
or  to  seasonal  vicissitudes. 

It  is  wholly  different,  as  we  know,  with  the  members 
of  the  vegetable  kingdom  existing  around  and  amongst 
these  inanimate  things.  The  seasonal  changes  shown  by 
them  are  familiar  to  all.  The  putting  forth  of  the  leaf, 
the  period  of  active  growth,  the  bloom  of  flowers,  the 
shedding  of  seed,  the  fading  and  fall  of  leaves,  are  so 
many  manifestations  of  an  internal  activity  which  dis- 
play themselves  with  never-failing  regularity. 


2  THE    USES    AND    ORIGIN 

Plants  respond,  however,  to  more  definite  external 
changes  than  those  dependent  upon  seasonal  mutations. 
Their  flowers  open  and  shut  at  particular  hours  of  the 
day,  in  accordance  with  the  varying  amounts  of  heat  and 
sunlight  falling  upon  them.  They  grow  more  rapidly 
hy  night  than  hy  day,  though  as  a  general  rule  the  activity 
of  their  internal  changes  is  closely  related  to  the  degree 
of  heat  to  which  they  are  subjected.  Again,  whilst  they 
generally  grow  best  in  directions  where  they  meet  with 
most  air  and  light  (not  because  of  the  latter  agency,  but 
rather  on  account  of  the  heat  which  goes  with  it),  many 
of  them  will,  in  the  course  of  a  few  days  or  within 
shorter  periods,  bend  very  perceptibly,  so  as  to  bring  them- 
selves more  under  the  influence  of  this  latter  agent. 

Amongst  some  representatives  of  plant  life,  the  corre- 
spondence between  internal  and  external  changes  is 
undoubtedly  less  obvious  than  in  many  of  the  instances 
just  referred  to.  Thus  is  it  with  the  black  or  grey  film 
of  Lichen  which  marks  as  with  a  patch  of  paint  the  damp 
surface  of  some  weather-beaten  rock.  Yet,  watch  it  care- 
fully from  time  to  time,  and,  even  in  this  lowly  form  of 
life,  responsive  though  sluggish  changes  may  be  detected, 
sufficient  to  remove  it  from  the  category  of  inanimate 
things  to  which  the  rock  itself  belongs. 

The  comparative  complexity  of  life  exhibited  by  mem- 
bers of  the  vegetable  kingdom  is,  however,  small ;  and 
for  this  two  principal  causes  may  be  cited. 

(1.)  As  a  rule — to  which  there  are  only  few  though 
interesting  exceptions,  to  be  mentioned  further  on — they 
subsist  on  inorganic  materials,  deriving  their  food  from 
the  gaseous  or  dissolved  mineral  elements  existing  in  the 
air  or  water  with  which  their  surfaces  are  bathed.  In 
their  natural  or  healthy  state  plants  decompose  carbonic 
acid,  fixing  its  carbon  and  setting  free  its  oxygen.     They 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  3 

decompose  water,  so  as  to  retain  its  hydrogen ;  whilst 
they  also  abstract  nitrogen  either  directly  from  the 
atmosphere,  or  indirectly  from  the  nitrate  of  ammonia 
formed  therein  and  brought  to  the  soil  in  refreshing 
showers.  This  work  of  decomposition,  under  the  in- 
fluence of  light  and  heat,  goes  hand  in  hand  with  one  of 
an  opposite  kind,  resulting  in  the  elaboration  of  those 
organic  and  living  compounds  which  enter  into  the  com- 
position of  vegetal  tissues. 

(2.)  Then  again,  as  a  rule,  plants  exhibit  no  inherent 
powers  of  movement  other  than  those  connected  with 
their  growth.  The  movements  of  the  Sunflower  and  its 
allies  are  exceptional ;  and  there  are  very  few  plants 
which  more  or  less  immediately  respond  to  a  touch  by  a 
movement,  in  the  way  that  the  Sensitive-plant  or  the 
Venus  fly-trap  is  known  to  do.  To  this  subject,  however, 
and  to  the  causes  of  such  motions  in  plants,  it  will  be 
necessary  to  return.  For  the  present  it  is  of  importance 
to  recollect  that  plants  do  not  move  at  all  in  search  of 
food. 

The  comparative  simplicity  of  the  life-processes  of 
plants  is  in  the  main  due  to  these  two  peculiarities.  They 
are  also,  perhaps,  the  most  fundamental  attributes  of 
plants  as  distinguished  from  animals.  This  subject  is 
well  worthy  of  our  brief  attention,  since  if  its  considera- 
tion should  lead  us  to  anything  like  a  correct  apprecia- 
tion of  the  mode  in  which  some  of  the  simplest  vegetal 
organisms  differ  from  some  of  the  simplest  animal  organ- 
isms, this  insight  may — apart  from  its  own  intrinsic 
interest — prove  of  the  highest  importance  in  regard  to 
our  present  inquiry.  It  may  enable  us,  in  a  measure,  to 
comprehend  why  a  Nervous  System  is  absent  from  Plants, 
and  why  it  comes  into  existence  in  Animals.  It  may  help 
us  further  to  comprehend  why  this  nerve  tissue  gradually 


4  THE   USES    AND    ORIGIN 

increases  in  complexity  in  ascending  to  more  and  more 
highly  organized  types  of  animal  life. 

#  ^  '3p  ^  V 

In  the  present  day  it  is  commonly  admitted  that  many 
of  the  lowest  forms  of  life  cannot  positively  be  assigned 
either  to  the  Vegetal  or  to  the  Animal  Kingdom.  Their 
characters  as  living  things  are  not  sufficiently  specific  or 
constant  to  enable  us  to  say  that  they  belong  to  one  king- 
dom rather  than  to  the  other.  In  some  of  their  life-phases 
such  organisms  seem  to  display  the  attributes  of  vegetal 
life,  whilst  in  others  those  of  animal  life  are  no  less 
pronounced.  They  constitute,  in  fact,  an  underlying 
indeterminate  plexus  of  changeable  and  more  or  less 
related  forms,  appearing  now  as  animals,  now  as  plants — • 
and  they  may  give  rise  to  descendants,  or  to  a  series  of 
them,  totally  unlike  themselves  and  their  own  immediate 
ancestors.  Amongst  such  forms  variability  reigns  supreme. 
These  creatures  of  circumstance,  which  become  metamor- 
phosed in  a  most  striking  and  apparently  irregular  manner, 
the  writer  has  proposed*  to  include  under  the  general 
designation  of  '  ephemeromorphs.'  True  *  species,'  in 
the  strict  acceptation  of  the  term,  are  not  to  be  found 
amongst  them. 

Starting  from  this  neutral  and  changeable  ground, 
however,  forms  of  life  appear  that  habitually  reproduce 
their  like,  either  directly  or  indirectly  ;  some  of  which  are 
unmistakably  members  of  the  vegetal  kingdom,  whilst 
others  are  no  less  characteristic  representatives  of  the 
animal  world. 

Owing  to  the  frequency  and  rapidity  with  which  transi- 
tions from  vegetal  to  animal,  or  from  animal  to  vegetal, 
modes  of  growth  have  been   observed  to  occur  amongst 

♦  "  Beginnings  of  Life,"  1872,  vol.  ii.  pp.  559,  571. 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  5 

*ephemeromorplis,'  we  are  compelled  to  believe  that 
such  passages  from  the  one  mode  of  molecular  composition 
and  activity  to  the  other,  may  be  determined  without  any 
great  difficulty  by  internal  chemico-nutritive  changes, 
whether  these  latter  have  or  have  not  been  in  part  induced 
by  external  influences.  Such  transitions  from  vegetal  to 
animal  modes  of  life,  or  the  reverse,  are  regarded  by  the 
writer  as  comparable  with  some  well-known  metamor- 
phoses of  form  and  nature  amongst  simpler  kinds  of  matter.* 

It  is  certain,  as  Prof.  Graham  showed,  that  one  and  the 
same  saline  substance  may  exist  with  its  molecules  now 
in  the  crystalloid  and  now  in  the  colloidal  mode  of  aggre- 
gation, according  to  the  different  influences  under  which 
it  has  been  produced,  or  to  which  it  has  been  afterwards 
subjected.  This,  for  instance,  is  the  case  with  silica,  with 
the  sesquioxides  of  chromium  and  iron,  and  with  other 
mineral  substances.  On  the  contrary,  it  is  also  known  that 
certain  typical  colloids  ma}",  under  some  conditions,  be 
converted  into  crystalloids. 

Again,  transformations  of  a  similar  order,  though  of 
different  degrees  of  complexity,  are  met  with  amongst 
saline  and  elementary  substances,  when  these  assume 
different  '  allotropic'  conditions.  Well  known  illustrations 
of  this  kind  of  metamorphosis  are  met  with  in  the  dif- 
ferent interchangeable  states  of  carbon,  of  phosphorus, 
and  of  sulphur.  The  passage  from  one  to  the  other 
allotropic  state  amongst  these  elementary  substances  may 
take  place  either  with  difficulty  or  with  comparative  readi- 
ness, though  the  ease  and  celerity  with  which  analogous 
transformations  are  effected  in  the  case  of  certain  saline 
substances  is  still  more  interesting  in  its  bearing  upon  the 
transformations  of  simple  living  units.     No  better  instance 

*  "Beginnings  of  Life,"  vol.  ii.  pp.  38,  55,  82. 


6  THE    USES    AND    ORIGIN 

can  be  selected  than  the  case  of  mercuric  iodide,  a  sub- 
stance well  known  to  exist  in  two  totally  distinct  crystalline 
forms  which  differ  also  in  colour.  Watts  says — "  The  red 
crystals  turn  yellow  when  heated,  and  resume  their  red 
tint  on  cooling.  The  yellow  crystals  obtained  by  subli- 
mation retain  their  colour  when  cooled ;  but,  on  the 
slightest  rubbing  or  stirring  with  a  pointed  instrument, 
the  part  which  is  touched  turns  scarlet,  and  this  change 
of  colour  extends  with  a  slight  motion,  as  if  the  mass  were 
alive,  throughout  the  whole  group  of  crystals  as  far  as 
they  adhere  together." 

Thus,  it  would  appear  that  the  phenomena  of  allo- 
tropism  and  dimorphism,  and  the  fluxes  from  the  crys- 
talloid to  the  colloid  state  and  the  reverse,  are  strictly 
comparable  with  the  transformations  from  the  vegetal  to 
the  animal,  and  from  the  animal  to  the  vegetal,  modes  of 
growth  so  common  amongst  '  ephemeromorphs.'  The 
members  of  the  animal  and  the  vegetal  worlds  may  be 
regarded  as  self-multiplying  and  progressively  varying 
products,  resulting  from  developments  which  are  con- 
tinually taking  origin  from  what  may  be  regarded  as 
different  allotropic  states  of  Living  Matter. 

-y^  *  *  *  * 

Of  the  organisms  appearing  as  constituents  of  the 
ephemeromorphic  assemblage  of  vital  forms,  x^mcebaB  may 
perhaps  be  cited  as  the  simplest  types  of  unquestionably 
animal  life;  just  as  some  of  the  smallest  Confervae  or 
Moulds  are  amongst  the  simplest  known  forms  of  the 
vegetal  type  or  mode  of  growth. 

ConferviB  or  Moulds,  after  the  fashion  of  plants  generally, 
feed  upon  the  inorganic  elements  existing  around  them 
either  in  water  or  in  air ;  Amoebae,  after  the  manner  of 
animals  generally,  feed  upon  matter  which  is  either  living 
or  which  has  once  lived.     This  difference  between  plants 


Chap.  L]  OF    A    NERVOUS    SYSTEM.  7 

and  animals  in  tlieir  mode  of  nutrition  is  so  fundamental, 
BO  much  depends  upon  it,  that  we  shall  find  it  worth  our 
while  to  inquire  a  little  more  particularly  how  the  depar- 
ture from  the  more  primordial  mode  of  nutrition,  met 
•with  amongst  animals,  can  be  accounted  for. 

If  we  examine  some  simple  vegetal  unit  through  a 
microscope — the  germ  from  which  a  Conferva  grows,  for 
instance — we  find  it  exhibiting  no  distinct  changes  of 
form ;  and,  if  unprovided  with  one  or  more  vibratile 
filaments,  it  also  shows  no  movements  from  place  to 
place.  It  manifests  no  tendency  to  seize,  nor  has  it  any 
means  of  taking,  solid  food.  As  soon,  therefore,  as  the 
changes  incident  upon  the  active  growth  of  such  a  unit 
have  ceased,  the  outer  portion  of  its  substance  remains 
constantly  in  contact  with  the  medium  in  which  it  lives, 
and  shortly  becomes  modified.  It  condenses  and  is 
otherwise  changed  into  an  investing  envelope,  which 
commonly  goes  by  the  name  of  a  '  cell- wall.'  In  the 
Amoeba,  on  the  other  hand,  we  have  an  organism  which, 
like  the  fabled  Proteus,  is  for  ever  changing  its  form. 
It  is  composed  of  a  clear  jelly-like  material,  endowed 
with  a  superabundance  of  that  intrinsic  activity  character- 
istic of  animal  life  generally.  Those  internal  molecular 
movements,  indeed,  which  are  inferred  to  occur  to  a 
marked  extent  in  all  living  matter,  seem  to  take  place  in 
it  in  a  pre-eminent  degree.  Its  whole  substance  shows  a 
mobility  of  the  most  striking  kind.  It  continually  moves 
through  the  water  or  over  surfaces,  by  alternate  projec- 
tions and  retractions  of  its  active  body-substance. 

Two  consequences  flow  from  this  high  inherent 
activity  of  the  Amoeba.  In  the  first  place,  owing  to  the 
creature's  rapid  alterations  in  shape,  no  one  portion  of  its 
substance  is  continuously  exposed  to  contact  with  its 
medium,  and,  as  a  consequence,  that  first  step  in  orgau- 


8  THE    USES    AND    ORIGIN 

ization,  above  referred  to  in  connection  with  tlie  Conferva 
unit,  does  not  take  place.  So  long  as  the  Amoeba  remains 
in  full  vigour  and  constantly  changes  its  shape,  a  cell- wall 
cannot  be  formed. 

Secondly,  during  the  movements  of  the  organism  from 
place  to  place,  portions  of  its  projected  bod}'-substance 
come  into  contact  with  other  more  minute  organisms, 
such  as  unicellular  algae  and  diatoms,  or  with  small 
portions  of  organic  refuse,  and  these  are  oftentimes 
drawn  into  its  interior  when  the  projections  with  which 
they  are  in  contact  are  retracted.  The  activity  of  the 
AmoBba  and  its  allies  is  excited  by  contact  with  matter  of 
this  and  of  other  kinds,  though  inorganic  fragments  are 
subsequently  rejected. 

The  surplus  inherent  activity  of  the  Amoeba  being, 
therefore,  one  of  the  immediately  determining  causes  of  its 
absorbing  solid  food,  may  also  be  regarded  as  one  of  the 
causes  of  its  departure  from  the  more  elementary  mode 
of  nutrition  met  with  amongst  the  simpler  or  less  vitalized 
organisms  from  which  it  has  been  derived. 

A  word,  however,  is  required  as  to  the  *  selective  * 
power  which  the  Amoeba  seems  to  manifest. 

A  magnet  *  selects '  minute  fragments  of  iron  or  steel 
from  any  heap  of  heterogeneous  particles  containing 
such  matter  with  which  it  may  be  brought  into  contact. 
Certain  plants,  also,  such  as  the  Sun-dew  and  the  Venus 
fly-trap,  '  select,'  and  seem  capable  of  discriminating, 
nitrogenous  from  other  substances  with  which  they  come 
into  contact.  The  leaves  of  these  plants,  however,  possess 
no  nervous  tissues  of  any  kind  ;  so  that  the  fact  that  they 
seem  to  '  select '  nitrogenous  substances  merely  implies 
the  existence  of  some  relation  between  the  molecular  com- 
position and  activities  of  the  leaves  and  those  of  such 
substances — by   virtue   of  which    mutual    contact   keeps 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  9 

up  a  state  of  excitation  in  the  tissues  of  the  plant.  Simi- 
larly, there  must  be  some  definite  molecular  relation 
between  a  magnet  and  pieces  of  iron  or  steel,  leading  to 
their  '  selection '  whenever  they  come  within  certain  degrees 
of  proximity.  In  the  latter  case  we  have,  unquestionably, 
to  do  with  problems  of  molecular  physics  ;  and  in  the  case 
of  the  affinity  which  seems  to  exist  between  the  nerveless 
Amoeba  and  the  organic  fragments  or  minute  living  things 
which  it  absords  as  food,  we  probably  have  to  do  with  an 
allied  problem.  There  may  be  differences  of  degree,  but 
none  of  kind ;  all  must  be  included  as  problems  of  mole- 
cular physics. 

At  any  rate,  be  the  cause  what  it  may,  the  coming  into 
contact  of  a  fragment  of  organic  matter  with  projected 
portions  of  the  substance  of  an  Amoeba  is  followed  by  the 
closure  of  this  mobile  substance  round  it.  The  organic 
mass  is  gradually  drawn  into  the  interior  of  our  Proteus, 
where,  after  being  thus  appropriated,  it  slowly  disappears 
by  a  rudimentary  process  of  *  digestion.'  After  feeding, 
in  this  way,  and  assimilating  the  organic  matter  taken  into 
its  interior,  the  Amoeba  rapidly  increases  in  size,  and  per- 
haps still  continues  its  active  movements.  Or,  as 
happens  at  other  times,  its  movements  may  cease  :  the 
creature  grows  sluggish  from  over-feeding,  and  then,  as  a 
consequence  of  its  motionless  condition,  its  outer  layer 
soon  becomes  differentiated  into  a  cyst-wall. 

Simple  as  this  mode  of  nutrition  may  appear  to  those 
who  are  familiar  with  it,  its  initiation  in  the  Amoeba  is 
followed  by  consequences  of  the  most  profound  importance. 
The  assimilation,  after  such  a  fashion,  of  alread}^  elaborated 
organic  matter  is  strongly  calculated  to  increase  that  high 
degree  of  vitality  which  originally  led  the  organism  to 
take  in  solid  food.  This  mode  of  nutrition,  in  fact,  entails 
fn  liberation  within  the  organism  of  much  of  the  molecular 


10  THE    USES    AND    ORIGIN 

motion  which  was  potential  in  its  food ;  and  molecular 
motion  thus  liberated  becomes  a  cause  of  further  active 
movements  in  the  organism — provided  its  constitution  is, 
at  the  time,  able  to  accommodate  itself  to  such  powerful 
internal  causes  of  chanpje.  Where  it  is  not  in  such  a 
condition  the  assimilation  of  much  solid  food  is  followed  by 
an  interval  of  apparent  rest,  during  which  a  thorough  re- 
adjustment of  the  molecular  constitution  of  the  organism 
occurs.  In  the  latter  case  the  encysted  mass  of  living 
matter  may  after  a  time  divide  into  a  swarm  of  smaller 
though  most  active  Monads.  Or  else  traces  of  higher 
organization  may  reveal  themselves  in  the  encysted  mass 
as  a  whole — so  that  the  previous  Amoeba  shortly  emerges 
from  its  cyst  as  an  active  creature  of  larger  size  and  higher 
type. 

Ciliated  Infusoria,  Kotifers,  and  other  forms  of  animal 
life  of  different  degrees  of  complexity,  may  take  origin  in 
such  encysted  masses  of  protoplasm,  forming  the  resting 
stages  of  previously  active  Amoebae.*  The  extent  to  which 
this  occurs,  however,  and  the  real  significance  of  the  pro- 
cesses, are  subjects  upon  which  all  naturalists  are  far 
from  being  of  the  same  opinion. 

Be  the  interpretation,  however,  what  it  may,  the  fact 
remains  that  Ciliated  Infusoria,  Rotifers,  and  other 
organisms  may  be  seen  to  develop  directly  from  encysted 
matrices  of  vegetal  or  of  Amoeboid  origin.  Nay  more,  any 
forms  of  the  animal  series  thus  initiated  exhibit,  in  an 
even  more  marked  degree,  the  fundamental  properties  of 
the  Amoeba — the  power,  that  is,  of  executing  well- 
marked  independent  movements  and  of  feeding  upon 
solid  food.  And  as  channels  for  the  reception  of  such  food 
become  more  and  more  formed,  we  may  find  the  organ- 

*  "Beginnings  of  Life,"  vol.  ii.,  chaps,  xxi.  and  xxii. 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  11 

ism's  increasing  powers  of  movement  more  definitely 
ministering  to  this  capacity.  Its  motions,  instead  of 
being  wholly  at  random,  show  more  and  more  signs  of 
purposiveness — they  become,  to  an  increasing  degree, 
subservient  to  the  capture  of  food. 

Look,  then,  at  the  differences  already  indicated  both  in 
grade  of  organization  and  mode  of  life,  by  virtue  of  which 
even  the  simpler  kinds  of  animals  become  strikingly  un- 
like vegetal  organisms. 

The  unit  of  vegetal  life  before  it  has  attained  any  great 
size  exhibits,  by  reason  of  its  lower  degree  of  inherent 
activity,  a  tendency  to  undergo  the  first  stage  of  organiza- 
tion, that  is,  to  develop  a  cell-wall  which  imprisons  the 
more  active  living  matter  within  and  causes  it  to  under- 
go certain  secondary  modifications.  Before  this  occurs, 
however,  the  vegetal  unit,  if  it  does  not  divide,  may  seg- 
ment or  bud ;  the  bud  grows  into  a  unit  similar  to  its 
parent,  and  this  in  its  turn  may  also  segment  or  bud.  By 
repetition  of  such  a  process  motionless  cellular  organisms 
are  produced,  which,  though  presenting  almost  endless 
differences  in  form  and  in  the  ultimate  arrangement  of 
their  units,  are  in  the  main  composed  of  mere  aggrega- 
tions of  similar  parts — these  being  not  solid  units  of  pro- 
toplasm, but  mostly  vesicular  elements,  in  which  a  cavity 
filled  with  fluid  contents  is  bounded  by  a  layer  of  pro- 
toplasm and  outside  this  by  an  inert  cell-wall.  We  may 
have,  in  the  more  simple  combinations,  long  strings  of 
such  elements  forming  cellular  filaments,  as  in  the  Con- 
fervse  and  other  thread-like  algae ;  or  we  may  have  flat 
cellular  expansions,  such  as  exist  and  brighten  many  a 
rock  pool,  in  the  rich  green  fronds  of  Ulva.  Organisms  like 
this  present  us  with  life  changes  of  extreme  simplicity. 
If  they  move  it  is  because  they  are  swayed  to  and  fro  by 


12  THE    USES    AND    ORIGIN 

the  elements.  They  require  not  to  seek  their  food,  since 
the  inorganic  materials  and  simple  compounds  sufficing 
for  their  nutrition  habitually  exist  around  and  in  contact 
with  them. 

On  the  other  hand,  in  animal  organisms  next  above  the 
Amoeba — such  as  the  various  forms  of  Ciliated  Infusoria 
and  Rotifers — well-marked  powers  of  locomotion  are  dis- 
played, and  we  have  to  do  with  creatures  which,  if  they 
do  not  '  seek,'  at  all  events  seize  and  swallow  solid  food. 
We  find  in  the  latter  of  these  forms  of  pond  life,  distinct 
channels  through  which  food  is  taken  in  and  absorbed  ; 
we  have  glandular  structures  of  various  kinds ;  we  have 
organs  of  locomotion,  internal  and  external.  Thus,  though 
we  have  not  yet  been  able  to  detect  with  any  certainty 
even  the  rudiments  of  a  nervous  system,  the  grade  of 
vitality  of  these  animal  organisms  must  be  at  once  ad- 
mitted to  be  notably  higher  than  that  of  plants.  The 
degree  of  correspondence  existing  between  such  creatures 
and  their  surroundings  is  already  much  more  varied 
than  that  existing  between  vegetal  organisms  and  their 
medium ;  and  this  kind  of  complexity  of  relation  steadily 
increases  in  animal  organisms  only  a  little  higher  than 
those  to  which  we  have  already  referred.  Their  responses, 
moreover,  to  the  varied  external  influences  to  which  they 
have  become  amenable  are  effected  by  movements  direct, 
rapid,  and  comparatively  complex — the  motions  them- 
Belves  being  brought  about  by  muscular  contractions,  partly 
simultaneous  and  partly  successive,  and  mostly  occurring 
in  groups  which  are  definitely  related  to  difierent  external 
impressions.  Reference  to  a  few  of  their  common  muscular 
actions  will  illustrate  this. 

Conjoined  movements  of  the  head  and  its  appendages 
are  needed  for  the  seizure  of  fragments  serving  as  food ; 
and  these  motions  must  be  followed  by  certain  others  in 


CtiAP.  I.]  OF    A    NERVOUS    SYSTEM.  13 

the  upper  parts  of  the  alimentary  canal  before  the  morsel 
that  has  been  captured  can  be  swallowed.  A  series  of 
movements  of  this  kind  may  occur  in  response  to  soma 
touch  upon  the  external  surface  of  such  an  organism ; 
and,  after  a  rudimentary  sense  of  sight  has  once  been 
established,  impressions  produced  by  an  object  not  in  con- 
tact may  lead  to  complex  locomotions  in  pursuit,  followed 
by  others  for  capture,  and  others  again  for  the  swallowing 
of  food  or  prey.  The  sight  of  a  different  object  may,  how- 
ever, lead  to  movements  of  flight  rather  than  to  those 
of  pursuit.  The  organism  may  hasten  away,  to  avoid  a  pos- 
sible attack — since  in  the  past  this  kind  of  experience  may 
often  have  followed  the  appearance  of  a  similar  object. 

Again,  the  process  of  digestion  in  such  animal  organ- 
isms is  aided  by  certain  accessory  glandular  organs,  whose 
activity  is  stimulated  by  the  contact  of  food  with  different 
portions  of  the  alimentary  canal.  Absorption  of  the  pro- 
ducts of  digestion  is  either  simple  and  direct  from  the 
alimentary  canal  into  some  general  body-cavity  whose 
fluid  comes  into  contact  with  most  of  the  organs ;  or  it 
takes  place  through  definite  channels,  and  empties  itself 
into  a  circulatory  system  proper  in  which  blood  is  pro- 
pelled throughout  the  body  by  means  of  a  contractile 
heart  containing  one  or  more  chambers.  Glands  also 
exist  whose  office  it  is  to  modify  the  constitution  of  the 
blood.  There  may  be  either  gills  or  lungs  to  renovate 
it  by  contact  with  oxygen  and  to  get  rid  of  effete  products 
— though  in  this  latter  function  the  organs  of  respiration 
are  powerfully  aided  by  renal  and  other  emunctories. 

All  these  are  f auctions  having  to  do  with  the  preserva- 
tion of  the  life  of  the  individual,  though  another  set  of 
activities  also  come  into  play  in  animals  that  have  attained 
a  grade  of  organization  of  the  kind  to  which  we  are  refer- 
ring. These  new  activities  pertain  to  the  sexual  function — ■ 
2 


14  THE    USES    AND    ORIGIN 

leading  to  the  union  of  male  and  female,  the  begetting  of 
young,  and  the  consequent  perpetuation  of  the  species. 

Thus  it  may  be  dimly  gathered  how  complex  the  relation 
of  the  animal  organism  to  its  environment  soon  becomes, 
and  also  what  an  amount  of  interdependence  is  estabP.shed 
between  the  actions  of  the  several  parts  or  organs  of  the 
animal  economy.  The  contrast  between  the  animal  and 
the  vegetal  organism  in  both  these  respects  becomes  most 
marked. 

It  is  during  the  establishment  of  the  complex  relations 
above  indicated  between  an  animal  and  its  environment, 
and  between  the  several  parts  or  organs  of  an  animal,  that 
nervous  tissues  first  take  origin,  develop,  and  subsequently 
increase  in  complexity.  How  and  why  this  should  be  may 
become  a  little  more  plain  after  a  brief  consideration  of 
the  nature  of  simple  nervous  functions  and  structures, 
and  after  some  reference  to  the  manner  in  which  these 
increase  in  complexity,  not  only  in  the  individual  but  (by 
virtue  of  the  principles  of  heredity  and  '  natural  selection  ') 
during  the  life  of  that  succession  of  individuals  consti- 
tuting the  race  or  *  species '  to  which  the  organism 
belongs. 

From  what  has  been  already  said  it  will  be  seen  that 
the  preliminary  conditions  necessary  for  the  initiation  of 
a  Nervous  System  are,  first,  the  existence  of  a  living  sub- 
stance whose  excitability  is  high ;  and,  secondly,  the  pos- 
session by  such  substance  of  a  well-marked  contractile 
power.  This  statement  carries  with  it  the  implication 
that  the  living  matter  in  which  a  nervous  tissue  is  to 
develop  must  not,  in  the  first  place,  subdivide  itself  very 
minutely  into  separate  units ;  or,  at  all  events,  that  it 
must  not  become  differentiated  into  cells  with  fully  de- 
veloped cell-walls.    Much  of  the  substance  of  the  organism. 


Chap.  L]  OF    A    NERVOUS    SYSTEM.  15 

if  not  comparatively  structureless,  must  be  composed  of 
plastic  units  of  living  matter,  not  marked  off  from  one 
another  by  definite  and  lowly  vitalized  cell- walls. 

The  vegetal  mode  of  growth  is,  therefore,  as  already 
indicated,  precisely  of  such  a  kind  as  to  unfit  it  in  an 
eminent  degree  for  developing  any  notable  power  of  appre- 
ciating varied  external  impressions  and  yielding  immediate 
and  discriminative  responses  thereto. 

The  nearest  approach  to  such  powers  and  actions  in  the 
vegetal  world  is  met  with  amongst  the  so-called  ''  Insec- 
tivorous Plants,"  upon  whose  peculiarities  Mr.  Darwin 
has  lately  given  us  much  information.  If  we  dwell  for  a 
few  moments  upon  these  highest  manifestions  of  the  kind 
known  to  occur  amongst  plants,  the  reader  may  the  bettor 
comprehend  the  great  gulf  which  separates  the  vegetal 
from  the  animal  world  in  regard  to  their  respective  powers 
of  discrimination  and  motor  response. 

When  the  three  hair-like  projections  on  the  upper  surface 
of  the  leaf  of  the  Venus  fly-trap  are  touched,  they  almost 
instantly  communicate  a  stimulus  to  the  cells  on  each 
side  of  the  mid-rib,  whereby  some  change  is  induced  in 
them,  and  the  two  halves  of  the  leaf  are  made  to 
approach  one  another.  The  nature  of  the  change  has  not 
yet  been  fully  ascertained,  though  the  evidence  adduced 
by  Darwin  seems  to  show  that  it  is,  at  least  in  part,  due 
to  the  contractility  of  the  cells  above  mentioned.  A  simi- 
lar influence  appears  to  be  transmitted  from  the  glands 
that  tip  the  hair-like  projections  fringing  the  leaves  of  the 
Sun  dew,  to  certain  cells  near  the  base  of  these  bodies, 
whereby  motion  is  produced.  In  this  latter  plant,  a  very 
appreciable  interval  occurs  between  the  time  of  irritation 
pnd  the  answering  movement.  Mr.  Darwin  has  never 
known  the  interval  to  be  less  than  ten  seconds,  though 
even  in  the  one  case  in  which  it  took  place  so  rapidly  aa 


16  THE    USES    AND    ORIGIN 

this,  two  and  a  half  minutes  were  needed  for  the  hair,  or 
'tentacle'  as  it  has  been  termed,  to  move  through  an 
angle  of  45°.  As  a  rule,  the  rate  of  movement  is  even 
much  slower.  The  stimulus  which  provokes  movement 
may  come  to  the  base  of  a  marginal  tentacle  either  from 
its  own  sensitive  tip,  or  by  radiation  from  some  of  the 
shorter  hair-like  projections  near  the  centre  of  the  leaf 
whenever  their  terminal  glands  have  been  excited  by  con- 
tact with  a  foreign  body. 

The  transmission  of  a  stimulus  from  one  of  the  glands 
tipping  a  marginal  tentacle  in  the  Sun-dew,  to  certain  cells 
near  its  base,  though  consisting  only  of  molecular  move- 
ments, becomes  in  a  manner  visible,  owing  to  the  fact  that 
during  its  passage  the  protoplasm  within  the  cells  of  the 
tentacle  undergoes  certain  obvious  changes.  Protoplasm 
previously  in  a  state  of  uniform  diffusion  throughout  each 
cell,  is  caused  to  aggregate  into  masses  of  different  size 
and  shape  as  the  invisible  wave  of  molecular  movement 
passes  through  it.  This  '  aggregation '  is  therefoi-e  a 
visible  sign  marking  the  passage  of  the  invisible  stimulus. 
And  as  Darwin  points  out,  the  phenomenon  is  analogous 
in  certain  respects  to  that  which  occurs  when,  after 
stimulus,  an  invisible  molecular  change  traverses  a  nerve 
in  an  animal  organism.* 

The  same  observer  has  discovered  that  the  chief  delay 
in  the  transmission  of  the  stimulus  along  the  tentacle 
of  the  Sun-dew  is  caused  by  its  having  to  traverse  tho 
successive  cell- walls  which  lie  across  its  path.  At  each 
barrier  of  this  kind  an  appreciable  retardation  occurs,  as  is 
evidenced  by  the  interval  that  elapses  between  the  com- 
pleted aggregation  in  one  cell  and  the  commencement  of 
the  process  in  the  protoplasm  of  that  which  stands  next 

"Insectivorous  Plants."    1875,  p.  (33. 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  17 

along  the  line  traversed  by  the  stimulus.  It  has  been 
found  that  a  stimulus  radiated  from  the  centre  traverses 
the  leaf  in  a  longitudinal  more  rapidly  than  it  dobS  in  a 
transverse  direction — a  circumstance  apparently  to  be 
explained  by  the  fact  that,  in  the  longitudinal  direction, 
owing  to  the  elongated  shape  and  disposition  of  the  cells, 
the  stimulus  has  to  pass  through  a  smaller  number  of 
obstructive  cell-walls. 

The  irritability  and  answering  movements  just  described 
are,  however,  altogether  exceptional  events  in  plant  life  ; 
more  especially  if  we  refer,  as  at  present,  only  to  cases 
where  there  is  reason  to  suppose  it  possible  that  the  move- 
ments are  in  part  due  to  contractility,  rather  than  to  mere 
disturbance  of  tension  in  some  of  the  cells — movements 
of  the  latter  order  being  not  unfrequent  in  stamens,  seed- 
pods,  or  other  parts  of  plants.  Yet  even  in  these  plants, 
where  contractility  appears  to  exist  to  a  more  marked 
extent  than  in  any  other  known  members  of  the  vegetal 
kingdom,  there  is  no  development  of  a  specialized  con- 
tractile tissue,  and  still  less  is  there  an  appearance  of  any 
nerve  fibres  along  which  the  molecular  disturbance  consti- 
tuting the  stimulus  may  be  transmitted.  The  obstacles 
opposing  the  passage  of  the  stimulus,  to  which  reference 
has  been  made,  would  indeed  also  tend  to  impede  the 
formation  of  a  special  tissue  along  the  line  of  discharge. 

In  Animal  Organisms,  however,  we  have  a  highly  im- 
pressible and  very  active  variety  of  protoplasm,  the  units  of 
which,  particularly  as  met  with  in  the  lowest  forms  of 
animal  life,  do  not  go  on  to  the  formation  of  a  distinct 
cell-wall,  and  are  for  the  most  part  aggregated  into  mere 
Bemi- fluid  or  gelatinous  tissues  capable  of  transmitting 
vibrations  in  different  directions  with  the  greatest  ease. 

This  is  the  case,  for  instance,  in  Medusae,  which  are 
perhaps  the  lowest  animals  in  whom  a  nervous  system  la 


18  THE  USES    AND    ORIGIN 

met  with.  The  recent  investigations  of  G.  J.  Romanes* 
in  regard  to  this  subject  are  particularly  interesting, 
because  they  seem  to  show  such  a  system  actually  in  pro- 
cess of  evolution.  The  contractions  of  the  bell-shaped 
swimming  disc  of  common  Medusae  must  be  familiar  to 
most  dwellers  by  the  seaside,  and  we  now  learn  that  this 
part  is  lined  internally  by  a  very  thin  layer  of  highly 
contractile  protoplasm,  not  yet  presenting  the  definite 
characters  of  muscle.  We  learn  also  that  this  contractile 
layer  is  permeated  by  a  network  of  incipient  nerve  fibres, 
in  connection  with  rudimentary  ganglia,  near  its  free 
margin.  The  degree  of  irritability  of  these  altogether 
elementary  animal  tissues,  and  the  rate  at  which  stimuli 
traverse  them,  is  alike  remarkable,  and  far  ahead  of  what 
may  be  met  with  in  the  plants  in  which  analogous 
changes  are  most  marked, — such  as  the  Venus  fly-trap 
or  the  Sun- dew. 

According  to  Romanes  the  molecular  discharges  issuing 
from  a  single  rudimentary  ganglion,  in  the  swimming  bell 
of  a  large  Aurelia  weighing  thirty  pounds,  were  sufficient 
to  incite  vigorous  contractions  throughout  the  whole  mass 
— though  this  mass  weighed  30,000,000  times  as  much 
as  the  ganglion  itself.  When  all  the  ganglia  have  been 
removed,  he  has  found  that  a  wave  of  contraction,  starting 
from  any  part  of  the  disc  which  is  touched,  will  travel 
equally  in  all  directions  at  the  rate  of  a  foot  and  a  half 
per  second,  so  that  the  contraction  of  the  whole  bell  is 
practically  simultaneous — and  therefore,  in  marked  con- 
trast with  the  very  slow  bending  of  the  irritated  tentacle 
of  a  Sun- dew. 

Thus  the  preliminary  conditions  already  asserted  to  be 
necessary  for  the  initiation  of  a  nervous  system  are  here 
present  to  a  well-marked  degree,  and  in  notable  contrast 
*  "Phil.  Trans.,"  Part  I.,  1876. 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  19 

to  what  obtains  amongst  the  members  of  the  vegetable 
world. 

As  to  the  mode  by  which,  in  Medusae  or  other  low  types 
of  animal  life,  the  first  rudiments  of  a  nervous  system  are 
evolved,  only  a  few  brief  statements  can  be  made.  On 
this  subject  inferences  have  only  too  often  to  take  the 
place  of  positive  knowledge.  Fortunately,  however,  the 
data  on  which  such  inferences  may  be  based  are  now  fairly 
well  established,  thanks  more  especially  to  the  writings 
of  Herbert  Spencer* — whose  speculations  on  this  subject 
have  been  to  some  extent  confirmed  by  the  recent  investi- 
gations of  Komanes  and  Eimer. 

In  the  lower  forms  of  animal  life,  we  have  to  do  with 
a  body  substance  composed,  as  already  stated,  almost 
wholly  of  undifferentiated  protoplasm.  This  substance, 
if  not  *  sensitive '  in  the  strict  sense  of  the  term,  is 
highly  impressible — or  capable  of  receiving  a  stimulus — 
and  is  also  highly  contractile.  But  neither  the  impressi- 
bility nor  the  contractility  of  the  protoplasm  in  lower 
forms  of  animal  life  is  localized — both  properties  are,  so 
far  as  they  exist,  uniformly  possessed  by  all  parts  of  the 
organism.  In  some  of  the  larger  Ciliated  Infusoria,  in 
Gregarinse,  and  in  the  hydroid  Polyps,  distinct  rudimen- 
tary *  muscles  '  become  differentiated,  and  such  tissues  are, 
moreover,  now  known  to  exist  in  many  other  organisms  in 
which  no  traces  of  a  nervous  system  are  to  be  found. 
Muscular  tissue,  therefore,  makes  its  appearance  before 
nervous  tissue,  and  it  becomes  developed  in  those  situa- 
tions where  the  protoplasm  is  stimulated  to  undergo 
frequent  contractions. 

It  is,  in  fact,  one  of  the  most  fundamental  truths  in 
biology  that  the  performance   of  functions,   or,  in  other 

*  "  Principles  of  Psychology,"  vol.  ii.  p.  69. 


20  THE    USES    AND    OFvIGIN 

words,  the  occurrence  of  actions  of  any  kind  in  living 
matter,  tends  to  occasion  structural  changes  therein. 
Such  a  fact  is  implied  in  the  common  statement  that 
living  matter  is  an  organizable  matter.  We  suppose 
nothing  unusual,  therefore,  when  we  imagine  that 
frequently  recurring  contractions  in  any  one  portion  of 
living  protoplasm  will  almost  certainly  lead  to  a  structural 
change  therein.  And,  further,  we  are  warranted  in 
supposing  that  such  structural  change  will  be  of  a  kind  to 
favour  the  occurrence  of  the  actions  by  which  it  has  itself 
been  produced — that  is,  that  the  modified  protoplasm  will 
be  more  highly  contractile  than  the  original  protoplasm 
from  which  it  has  been  produced. 

But  what,  it  may  be  asked,  is  the  cause  of  these  locally 
recurring  contractions,  the  occurrence  of  which  is  supposed 
eventually  to  lead  to  the  production  of  muscular  tissue  ? 
Contraction  so  invariably  follows  upon  stimulation,  that 
■we  may  safely  say  the  cause  in  question  can  be  no  other 
than  the  incidence  of  certain  stimulations — and  we  pro- 
bably shall  not  be  very  far  wrong  if  we  suppose  that  these 
result  from,  or  take  their  origin  in,  shocks  or  other  physical 
impressions  upon  definite  though  related  parts  of  the 
external  surface  of  the  organism.  Its  form  or  its  mode 
of  progression  by  cilia  may  lead  it  to  come  into  contact 
with  external  objects  most  frequently  by  some  particular 
part  of  its  surface,  and  such  local  shocks  produce  waves  of 
molecular  movement,  which  pass  more  especially  in  some 
one  or  more  directions  and  act  as  stimuli. 

It  is  pretty  certain  that  impressions  or  shocks  made 
upon  protoplasm,  or  even  the  incidence  of  physical  agents 
such  as  light  or  heat,  liberate  molecular  movements 
therein,  and  that  these  molecular  movements  may  be 
transmitted  from  their  point  of  origin  through  it  in  all 
directions.      Yet  it  occasionally  happens,   owing   to   the 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  21 

shape  of  the  part  struck,  or  owing  to  the  fact  that  an 
impression  made  upon  one  region — say  a  tentacle — is 
usually  followed  pretty  quickly  by  a  second  impression 
made  by  the  same  moving  object  upon  another  surface 
region,  that  an  impression  or  stimulus  comes,  as  Herbert 
Spencer  points  out,  habitually  to  traverse  a  certain  path. 
Much  of  the  molecular  motion  consequent  upon  the  'stim- 
ulus' is  drafted  along  this  path.  This  being  so,  the  stim- 
ulus necessarily  tends  to  excite  contractions  in  particular 
parts,  and  thus  leads  to  the  differentiation  of  the  pro- 
toplasm of  such  parts  into  the  more  or  less  definite 
Muscular  Tissue  found  in  some  of  the  lowest  animal 
organisms. 

This,  however,  is  not  all.  The  localization  of  the  path 
of  the  stimulus  leads  to  structural  results  of  another 
kind.  Whenever  external  impressions  produce  molecular 
movements  which  traverse  with  frequency  some  definite 
path,  the  transference  of  such  movements  is  made  easier 
by  each  repetition,  and  there  is  a  tendency  to  the  initia- 
tion of  a  structural  change  along  this  path.  Just  as  the 
frequent  repetition  of  contractions  in  certain  parts  of  the 
protoplasm  leads  to  the  production  of  distinct  muscular 
tissues,  so  the  frequent  passage  of  a  wave  of  molecular 
movement  along  a  definite  track  through  protoplasm  or 
through  juxtaposed  plastides,  leads  to  the  differentiation 
of  the  protoplasm  thus  acted  upon.  At  first  the  actual 
structural  change  may  be  unrecognizable,  although  a  *  line 
of  discharge  '  may  have  become  established  along  which 
impressions  are  habitually  transmitted  with  ease,  as  seems 
to  be  the  case  with  the  majority  of  Medusae.  Ultimately, 
however,  by  the  constant  repetition  of  such  a  process,  we 
should  have  the  gradual  formation  of  an  actual  '  Nerve 
Fibre' — this  being  a  tissue  element  whose  special  use  and 
duty  is  to  transmit  molecular  movement,  and  which  may 


22 


THE    USES    AND    ORIGIN 


be   seen   in   its   earliest  form    as    a    barely  recognizable 
structure  in  Sarsia.* 

From  all  this  it  would  appear  that  the  primitive  '  nerve 
fibre '  is  a  structure  serving  to  connect  impressions  made 
upon  the  exterior  of  the  organism  with  certain  responsive 
muscular  contractions  quickly  following  thereupon.  This 
is  perfectly  true,  though  only  part  of  the  truth. 

The  path  taken  by  stimuli  from  impressible  surfaces  to 

muscles  is  not  generally 
the  shortest  and  most 
direct  route.  In  the 
great  majority  of  organ- 
isms these  paths  are 
more  or  less  bent  upon 
themselves.  Those  for 
ingoing  impressions  may 
run  nearly  parallel  with 
one  another  towards 
some  central  situation  ; 
and  thence  they  may  be 
distributed  to  muscles  in 
various  parts  of  the 
body — some  of  these 
being  perhaps  not  very 
distant  from  the  surface 
stimulated.  In  the  latter  case  the  track  of  the  stimulus 
wave  is  found  to  be  bent  at  an  acute  angle,  or  '  reflected.' 
At  the  turning  point  or  '  nerve  centre,'  whence  impres- 
sions are  distributed  outwards  in  various  directions  to 
muscles,  what  are  called  '  Nerve  Cells  '  become  developed. 

*  Since  the  above  was  written  and  in  type  the  observations  of 
Sohiifer  (Proceed,  of  Koy.  Soc,  January,  1878),  and  of  0.  and  K. 
Hertwif^,  have  revealed  the  existence  of  distinct  nerve  tissues  in 
several  species  of  Medusae. 


FiG.  1.-  Different  kinds  of  Nerve  Cells.    (Magni 
ficd  about  850  diameters.) 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  23 

These  bodies  are  interposed  so  as  to  constitute  part  of  the 
actual  path  of  the  stimulus  wave,  and  accordingly,  they 
may  be,  in  effect,  junctions  for  ingoing  impressions  or 
dividing  stations  for  out-going  impressions.  The  matter 
composing  them  seems  to  be  endowed  with  extreme  mole- 
cular mobility.  It  is  owing  to  the  multitudinous  com- 
binations of  these  bodies  with  one  another,  and  with 
ingoing  and  outgoing  fibres,  in  modes  which  will  be 
sketched  in  the  next  chapter,  that  the  complex  w^ork  of 
the  nervous  system  is  enabled  to  be  carried  on. 

Nerve  tissue,  in  the  lower  forms  of  animal  life,  is 
essentially  subservient  to  the  bringing  about  of  move- 
ments in  more  or  less  immediate  response  to  external 
shocks  or  other  localized  impressions,  or  of  movements 
and  glandular  activity  as  a  result  of  impressions  upon 
internal  surfaces.  These  various  movements  gradually 
become  more  definitely  related  and  appropriate  as 
responses,  in  proportion  as  the  organism  becomes  better 
able  to  discriminate  the  differences  between  the  several 
kinds  of  impressions  made  upon  different  parts  of  its 
surface. 

Even  amongst  Medusae  definite  responses  to  stimuli 
are  occasionally  met  with.  Thus  in  the  hemispherical 
Tiaropsis,  from  the  inside  of  which  hangs  a  long  funnel- 
like body  or  polypite,  this  structuie,  as  Romanes  says,  is 
found  to  be  capable  of  "  localizing  with  the  utmost  pre- 
cision any  point  of  stimulation  situated  in  the  bell.  For 
instance,  if  the  bell  be  pricked  with  a  needle  at  any 
point,  the  polypite  immediately  moves  over  and  touches 
that  point.  ...  If  immediately  afterwards  any  other 
part  of  the  bell  be  pricked,  the  polypite  moves  over  to 
that  part,  and  so  on."  From  this  it  may  be  concluded 
*'  that  all  parts  of  the  bell  must  be  pervaded  by  lines  of 
discharge,  every  one  of  which  is  capable  of  conveying  a 


24  THE    USES    AND    ORIGIN 

separate  stimulus  to  the  polypite,  and  so  of  enabling  the 
polypite  always  to  determine  which  of  the  whole  multi- 
tude is  being  stimulated.  .  .  .  It  is  no  doubt  a 
benefit  to  this  Medusa  that  its  polypite  is  able  to  localize 
a  seat  of  stimulation  in  the  bell;  for  the  end  of  the 
polypite  is  provided  with  a  stinging  apparatus,  and  is, 
besides,  the  mouth  of  the  animal.  Consequently,  when 
any  living  object  touches  the  bell — whether  it  be  an 
enemy  or  a  creature  serving  as  prey — it  must  alike  be 
an  advantage  to  the  Medusa  that  its  polypite  is  able  to 
move  over  quickly  to  the  right  spot,  in  the  one  case  to 
sting  away  the  enemy,  and  in  the  other  to  capture  the 
prey.   - 

It  is,  in  all  probability,  the  delicate  impressions  pro- 
duced by  contact  of  the  sea-water  with  the  surface  of  the 
organism,  acting  through  the  intermediation  of  tlie  rudi- 
mentary ganglia  near  the  edge  of  the  swimming-bell, 
which  tend  to  incite  its  apparently  *  spontaneous ' 
movements.  At  all  events,  when  these  little  bodies  are 
removed  the  habitual  rhythmical  contractions  of  the 
swimming-bell  cease,  and  a  single  stimulation  of  any 
portion  of  the  bell  is  then  followed  by  a  single  contraction. 
The  contrast  between  the  behaviour  of  such  an  animal 
and  one  which  is  uninjured,  is  very  striking. f 

Multiply  the  kind  of  correlation  above  typified,  and  it 
may  be  seen  that  as  organisms,  or  their  descendants, 
increase  in  tneir  ability  to  discriminate  diff'erent  impres- 
sions made  upon  them  from  without,  so  will  there  grow 
up  muscular  responses  suitable  to  each.  And  the  struc- 
tural modifications,  or  '  tissues,'  through  the  intervention 
of  which  any  of  these  impressions,  discriminations,  and 
responses  are  rendered  possible,  are  no  more  isolated  from 
others  which  the  creature  is  capable  of  receiving  or  making, 
*  "  Nature,"  vol.  xvi.  p.  290.  f  Loc.  cit.,  p.  231). 


Chap.  I.]  OF    A    NERVOUS    SYSTEM.  25 

than  is  any  one  cause  of  impressions  isolated  from  others 
with  which  it  may  be  associated  in  the  complex  web  of 
external  occurrences.  Each  acquirement  serves  as  a 
stepping-stone  to  the  next,  and  each  new  response  is 
made  easier  by  those  previously  rendered  possible.  In 
this  way  the  correspondence  between  the  organism  and 
the  outside  world  gradually  becomes,  as  Herbert  Spencer 
has  urged,  both  more  precise  and  more  complex.  By 
slow  degrees  a  more  and  more  harmonious  relationship 
between  the  two  is  brought  about,  the  degree  of  complexity 
of  which  we  are  left  to  gauge,  principally  by  an  esti- 
mation of  the  character  of  the  movements  executed  in 
relation  to  the  stimuli  from  which  they  immediately  or 
remotely  proceed.  We  have  at  first  to  do  with  mere 
simple  *  reflex '  actions ;  in  higher  forms  of  life  some  ot 
these  actions  increase  so  much  in  complexity  as  to  become 
worthy  of  the  name  '  instinctive  *;  whilst  in  still  higher 
organisms  we  have  what  are  called  '  intelligent '  actions 
in  increasing  proportion,  though  always  intermixed  with 
multitudes  of  others  belonging  to  the  *  instinctive  '  and 
to  the  *  reflex '  categories. 


CHAPTER     11. 

THE     STRUCTURE     OF    A   NERVOUS    SYSTEM NERVE    FIBRES, 

CELLS,    AND    GANGLIA. 

The  Nervous  System  in  all  higher  animals  is  composed  of 
nerve  fibres  and  nerve  cells,  together  with  an  intermediate 
basis  substance  in  those  parts  where  the  latter  units  are 
principally  clustered  together.  The  whole  forms  a  con- 
tinuous tissue,  variously  arranged  and  distributed  through 
the  bodies  of  animals,  and  differing  notably  in  its  de- 
velopment in  accordance  with  the  complexity  of  organiza- 
tion of  the  creature  of  which  it  forms  part. 

In  all  animals  a  certain  order  or  plan  is,  howeVer, 
recognizable  in  the  mode  of  arrangement  of  the  typical 
elements  of  the  nervous  system.  Thus,  without  exception, 
we  find  ingoing  nerve-fibres  proceeding  from  sense  organs, 
or  from  other  sensitive  parts,  to  groups  of  nerve  cells  more 
or  less  freely  connected  with  one  another  in  some  *  nerve 
centre.'  These  cells  are,  in  their  turn,  connected  with 
another  set  of  inter-related  nerve  cells,  situated  either 
close  to  or  at  a  distance  from  the  first ;  and  from  this 
second  group  of  cells  a  set  of  outgoing  nerve  fibres  pro- 
ceed, which  are  distributed  to  muscles  or  to  glands  in 
various  parts  of  the  body.  Nerve  elements  so  arranged 
constitute  the  functional  units  of  a  nervous  system.  This 
is  the  kind  of  mechanism  by  means  of  which  *  reflex 
actions '  are  brought  about ;  and  these  form  the  ground- 


CiiAP.  II.]    THE    STRUCTURE    OE    A    NERVOUS    SYSTKM.     27 

work  of  all  simple  modes  of  nervous  activity.  By  an 
indetinite  multiplication  of  such  combinations  of  nerve 
units,  variously  arranged,  stimuli  or  impressions  (repre- 
sented by  molecular  movements)  are  conducted  from  the 
various  sensitive  surfaces  or  parts  of  the  body  to  related 
nerve  centres,  and  are  thence  reflected  so  as  to  rouse  the 
activity  of  related  muscles  or  glands. 

The  groups  of  nerve  cells  above  referred  to,  together  with 
some  portions  of  their  related  fibres,  are  usually  aggre- 
gated so  as  to  form  distinct  and  separate  nodules  known 
as  '  ganglia.'     Those  in  connection  with  ingoing  (or  afi'e- 


FiG.  2.— Small  Sympathetic  Ganglion  (Human)  with  Multipolar  Cells.      Magnified 
about  400  diameters.     (Leydig.) 

rent)  fibres  are  commonly  spoken  of  as  '  sensory  gan- 
glia,' whilst  those  which  lie  at  the  roots  of  outgoing  (or 
efferent)  nerves  are  known  as  '  motor  gangha.' 

Two  or  more  sensory  gangha,  or  two  or  more  motor 
ganglia,  may  grow  together  into  a  single  mass  ;  or  what  is 
equally  common,  a  sensory  and  its  corresponding  motor 
ganglion,  or  two  or  more  pairs  of  these,  may  fuse  into  a 
single  larger  nodule,  which  may  be  called  a  '  nerve  centre.' 


28  THE    STRUCTURE    OF 

The  term  ganglion  is,  however,  commonly  applied  to 
any  round  or  ovoid  nodule  containing  nerve  cells,  whatever 
its  size  or  degree  of  internal  complexity.  Many  ganglia 
in  lower  animals,  which  are  typically  deserving  of  the 
name  as  regards  mere  form  and  separateness,  are  also, 
hy  reason  of  their  compound  nature,  true  nerve  centres. 
The  two  terms  are,  therefore,  to  a  considerable  extent, 
interchangeable. 

Fusions  of  ganglia  may  occur  during  the  development  of 
some  animals,  especially  if  they  pass  Ihrough  distinct 
phases  of  existence,  as  with  Insects  (figs.  39-41).  Similar 
changes  are  also  presumed,  by  believers  in  the  doctrine  of 
evolution,  to  occur  during  the  development  of  the  race,  since 
in  many  highly  organized  animals  we  may  find  a  large 
compound  ganglion  in  the  place  of,  and  doing  such  work 
as  falls  to,  two  or  more  smaller  separate  ganglia  in  simpler 
members  of  the  same  class  of  animals — for  example,  in 
different  forms  of  Crustacea  (figs.  34—36).  This  kind  of 
fusion  or  coalescence  of  primitive  ganglia  attains  its  maxi- 
mum in  the  brain  and  spinal  cord  of  vertebrate  animals. 

From  their  naked-eye  appearances  nerve  tissues  are  com- 
monly di\ided  into  '  grey '  and  '  white  '  matter.  The  grey 
matter  of  the  nervous  system  is,  for  the  most  part,  gan- 
glionic tissue,  in  which  nerve  cells  are  more  or  less  thickly 
clustered.  The  white  matter,  on  the  other  hand,  such  as 
we  find  in  the  brain  and  spinal  cord,  is  composed  of  an 
aggregate  of  nerve  fibres.  These  tissues  are  of  a  soft 
pultaceous  or  semifluid  consistence,  and  are  composed,  in 
the  main,  of  water,  of  phosphoretted  fats,  and  of  protein 
compounds.  The  amount  of  water  varies  from  75  to  85 
per  cent.  It  is  more  abundant  in  the  grey  than  in  the 
white  matter;  more  abundant  in  lower  than  in  higher 
animals ;  and  it  likewise  forms  a  larger  proportion  of  tho 


Chap.  II.]  A   NERVOUS    SYSTEM.  29 

nerve  tissues  of  younger  animals  than  of  those  in  whom 
the  nerve  centres  are  more  fully  elaborated.  The  chemical 
compounds,  entering  into  the  constitution  of  nerve  tissues, 
are  also  extremely  complex  and  very  unstable.  Thus,  both 
from  their  physical  and  chemical  composition,  it  is  thought 
that  waves  of  molecular  movement  are  easily  initiated  in 
and  easily  propagated  through  nerve  cells  and  fibres. 
Whether  these  molecular  '  waves '  or  *  currents '  in  nerve 
tissue  are  brought  about  by  virtue  of  mere  isomeric 
changes  or  by  actual  decompositions  occurring  in  their 
substance  is,  for  the  present,  extremely  doubtful.* 

Our  knowledge  of  the  exact  arrangement  of  the  ana- 
tomical elements  of  nervous  tissues,  as  well  as  of  their 
modes  of  development,  is  as  yet  merely  in  its  infancy.  We 
have  much  to  learn  concerning  the  actual  relation  of 
fibres  and  cells,  and  their  different  modes  of  continuity ; 
our  knowledge  of  the  structural  relations  existing  between 
different  centres  in  higher  animals  is  most  incomplete ; 
and,  concerning  the  various  kinds  of  peripheral  nerve  end- 
ings, much  doubt  and  uncertainty  also  prevail.  The  more 
difficult  questions  touching  nerve  evolution  and  development 
are  proportionately  further  from  their  ultimate  solution. 

But,  whatever  the  precise  mode  in  which  the  nerve 
cell  is  originally  evolved  in  the  race,  or  developed  in  the 
embryo  of  any  particular  animal,  it  is  perfectly  certain 
that  many  of  these  bodies  are  subsequently  found  in 
organic  continuity  with  nerve  fibres  and  with  one  another; 
so  that  (whatever  other  function  they  may  fulfil)  nerve 
cells  would  seem  to  form  meeting-points  or  termini, 
in  which  different  nerve  currents  arriving  at  and  passing 
through  clusters  of  such  bodies,  may  be  brought  into 
relation  with  one  another,  and  whence  they  are  certainly 
capable  of  being  diverted  into  new  directions. 

*  Spencer,  "  Principles  of  Psychology,"  vol.  i.  p.  20. 


80  THE    STRUCTURE    OF 

Without  entering  upon  any  discussion  as  to  the  differ* 
ences  existing  between  the  nerve  elements  of  higher  and  of 
lower  animals,  and  dwelling  but  briefly  upon  the  many 
differences  of  opinion  which  exist  in  regard  to  the  actual 
structure  and  relations  of  these  elements,  an  endeavour 
will  be  made  to  give  the  reader  some  notions  concerning 
their  most  probable  arrangement — such  notions  as 
may  enable  him  to  comprehend  the  descriptions  given  in 
succeeding  chapters  of  the  different  forms  of  the  nervous 
system,  as  well  as  of  the  nature  and  mode  of  composition 
of  that  portion  of  it  known  as  the  '  brain',  in  various  orders 
of  animals  till  we  come  to  man  himself.  In  this  way 
it  will  be  possible  for  the  reader  who  bestows  an  adequate 
amount  of  attention,  to  obtain  a  good  insight  as  to  the 
nature  of  some  of  the  most  definite  and  best-grounded 
notions,  which  are  at  present  either  actually  held  or 
warrantable,  concerning  the  structure  and  functions  of 
the  *  Brain  as  an  Organ  of  Mind.' 

Nerve  Fibres. — At  their  commencement  near  the 
internal  and  external  surfaces  of  the  body,  and  also  near 
their  endings  in  muscles  and  glands,  nerves  are  repre- 
sented by  extremely  fine,  almost  transparent  '  fibrils  '  from 

"6 0  0 00^^  to  ■nnuT'oTT^^^  ^^  ^^  ^^^^  ^^  diameter.  These 
fibrils  freely  interlace  with  one  another,  so  as  to  form 
minute  loops  and  plexuses,  and,  within  short  distances, 
they  often  vary  considerably  in  diameter  (L.  Beale). 

Much  might  be  written  were  we  to  attempt  to  discuss 
the  various  modes  in  which  the  fibrils  commence  or  termi- 
nate, and  their  precise  relation  to  other  tissue  elements  in 
various  parts  of  the  body  ;  but,  in  spite  of  the  great 
interest  attaching  to  these  questions,  they  cannot  be 
entered  upon  in  this  work.  A  slight  reference  to  the 
Bubject  is,  however,  made  (p.  67)  in  the  next  chapter. 


Chap.  II.] 


A    NERVOUS    SYSTEM. 


31 


The  ultimate  bundles  of  elementary  *  fibrils '  are 
gradually  aggregated-  into  larger  bundles,  or  'fibres,'  as 
they  recede  from  their  seats  of  origin  or  termination  and 
approach  the  nerve  centres  with  which  they  are  in  com- 
munication. These  smaller  bundles  soon  become  enve- 
loped in  a  very  delicate  membranous  sheath  (Schwann), 
whilst  the  component  fibrils  fuse  more  or  less  completely, 
so  that  the  fibre  appears  either 
structureless  (fig.  3),  or  merely 
shows  signs  of  fibrillation.  A  little 
further  on  these  still  small  fibres 
become  enveloped  by  a  layer  of 
white  semi-fluid  '  medullary  sub- 
stance,' which  lies  beneath  the 
membranous  sheath  of  Schwann, 
and  forms  a  white  border  to  the 
nerve  as  it  is  seen  on  micro- 
scopical examination.  Thus  a 
dark  borxlered,  ivhite,  or  medid- 
lated  nerve  fibre  is  formed. 

Such  dark-bordered  fibres  are 
at  first  very  slender ;  but  by  co- 
alescence with  others  of  the  same 
kind  larger  fibres  are  produced 
(fig.  4),  varying  in  man  from  x'ilooo^^^  *^  T o~o"o^^  ^^  ^^ 
inch  in  diameter.  The  central  portion  of  such  a  nerve 
fibre,  viz.,  that  lying  within  the  white  medullary  sheath, 
is  its  most  important  constituent ;  it  is  almost  translucent, 
and  is  known  as  the  axis  band  or  axis  cylinder.  In 
the  perfectly  fresh  state  it  shows  faint  traces  of  fibril- 
lation, but  unless  examined  with  care  it  may  api3ear 
structureless,  and  yield  no  evidence  to  the  microscopic 
observer  as  to  its  compound  nature.  Under  the  influence 
of  slight  traction,  or  by  imbibition  of  water,  these  medui- 


Fio.  3. — Human  Nerve  Fibres 
of  different  sizes  (Kolliker). 

a,  a,  a.  Healthy  fibres,  the 
largest  of  which  is  '  dark-bor- 
dered.' b,  b.  Fibres  altered  by 
exposure.  Magnified  350  dia- 
meters. 


32  THE    STRUCTURE    OF 

lated  nerve  fibres  speedily  undergo  chanoe.     They  then  not 
unfrequently  assume  an  irregular  or  varicose  appearance — • 


PiO.  4.— Small  Branch  of  a  Muscular  Nerve  of  the  Frog,  near  its  Termination, 
showing  divisions  of  the  Fibres.  Magnified  350  diameters  (KoUiker).  <f,  into  two  ; 
h,  into  three. 

principally    owing    to    changes    in    the  white    medullary 
sheath  (fig.  3,  h,  h). 

The  use  of  this  white  investin<]C  substance  is  not  known. 


Chap.  II.] 


A    NERVOUS    SYSTEM. 


33 


It  is  absent  from  the  peripheral  extremities  of  the  nerves, 
and  it  is  absent  also  from  their  central  extremities,  at  the 
points  where  the  fibres  approach  or  depart  from  the  nerve 
cells.  Both  it  and  the  membranous  investing  sheath  have 
been  of  late  ascertained  to  be  regularly  interrupted  at 
comparatively  short  distances,  so  that  such  nerve  fibres 
have  the  appearance  of  being  constricted  in  these  situa- 
tions (Ranvier). 

Nearly  all  visceral  nerves,  as  well  as  the  fibres  of  the 
olfactory  and  some  others,  do  not  possess  this  medullary 
sheath,  to  which  the  dead  white  colour  of  the  great  ma- 
jority of  nerve  fibres  is  due.  They  are,  therefore,  semi- 
translucent  or  grey 
in  tint,  and  are 
commonly  known  as 
the  2^cde,  gelatinous 
or  non-medullated 
fibres  (fig.  5).  Their 
averaofe  thickness  is 


about  7i^(7f)  0^1^  of  an 
inch  ;  and  they  dif- 
fer from  the  dark 
bordered  fibres  prin- 
cipally in  the  ab- 
sence of  the  medul-  J''';  '•-^'^''^^^^T  ^TlJ'"^"""  r°™  'a%?''^ 

(Henle).      Magnified   about  400   diameters.      A,   Fibre 
lary  sheath.       They    showing   its  constituent  fibrlUse  (d.);   a,  a,   Nuclei  in 
,  T    1  •       i    naembrauous  sheath. 

present  a    distmct 

appearance  of  fibrillation,   are  surrounded  by  a  delicate 

membranous  envelope,  and  the  larger  fibres  are  similarly 

formed   by  the  running  together  of    fibrils   and    smaller 

fibres. 

Nerve  fibres  thus  compounded,  both  dark  bordered  and 
pale,  similarly  tend  to  aggregate  into  cords  or  bundles  of 
different  sizes,    the  fibres  of   which    run    parallel  to  one 


34  THE    STRUCTUllE    OF 

another,  and  are  invested  by  a  sheath.  These  again,  in 
their  course  towards  the  centre,  collect  into  larger  and 
larger  bundles,  the  different  elements  of  which  are  all 
bound  together  into  one  white  trunk  or  *  nerve  '  (fig.  6), 
by  means  of  a  firm  connective  tissue  envelope,  which 
sends  thinner  investing  prolongations  in  amongst  the 
constituent  cords. 

These  '  nerves '  of  various  sizes  frequently  contain 
within  the  same  bundle  both  ingoing  and  outgoing  fibres, 
and  are  then  known  as  '  mixed  nerves  '.  Others  contain 
only  'sensory',  or  only  'motor'  fibres.  In  their  course 
nerves   often   communicate   freely    one   with    another   by 


Fig.  6.— Portion  of  the  Tnink  of  a  Nerve,  consisting  of  many  smaller  Cords 
wrapped  up  in  a  common  Sheath  (Quain  after  Sir  C.  Bell),  a,  the  nerve  ;  b,  a  single 
cord  drawn  out  from  the  rest.     Magnified  several  diameters. 

means  of  branches.  Such  communicating  branches  are 
especially  numerous  in  the  course  of  the  visceral  nerves, 
and,  when  ma  ay  occur  amon(]^st  some  particular  set  of 
cords,  what  is  termed  a  '  plexus  '  is  formed  (fig.  7).  In  these 
plexuses  the  individual  nerve  fibres  do  not  undergo 
division.  Some  of  them  merely  leave  one  bundle  or  cord 
and  pass  to  another,  with  the  fibres  of  which  they  are 
ultimately  distributed,  either  to  muscles  or  to  nerve 
centres. 

The  smaller  medullatcd  nerve  fibres  unite,  so  far  as  we 
know,  only  near  their  commencements,  and  the  larger 
motor  fibres  only  undergo  bifurcation  near  their  termina- 
tions in  muscles  or  glands  (fig.  4).  The  fibrils  or  ele- 
mentary constituents  of  the  fibres  probably  do  not  divide 


Ckap.  II.] 


A    NEIIVOUS    SYSTEM. 


35 


at  all.  They  are  to  be  regarded  as  single  channels  (however 
devious  their  course  rnay  be),  along  each  of  which  separate 
stimulus-waves  are  capable  of  being  transmitted.    We  can 


Fig.  7. — The  Cervical  Plexus,  composed  by  interlacements  of  the  last  four  cervica 
(1,  2,  3,  4)  and  the  first  dorsal  nerves  (5).  The  various  branches  (6-21)  are  distributed 
to  the  shoulder,  arm,  fore-arm,  and  hand.     (Sappey  after  Hirschfeld.) 

* 

speak  here  only  of  probability,  as  this  is  a  subject  neces- 
sarily beyond  the  reach  of  actual  observation. 


Nerve  Cells  vary  much  in  size  and  shape — the  smallest 
being  about  g^Q^-Qth,  whilst  the  larger  may  be  3-^o^h  of 
an  inch  or  more  in  diameter.  They  are  more  or  less 
granular  bodies,  each  of  which  contains  a  large  nucleus, 
and  within  this  an  unusually  distinct  'nucleolus'  (figs. 
1  and  8).  Near  the  nucleus  a  heap  of  yellowish  or 
orange  coloured  pigment  granules  may  often  be  seen.  The 
substance  of  the  cell  is  continued  into  two  or  many  '  pro- 


86 


THE    STRUCTURE    OF 


Fig  8  -Gu.<nioii  Cell  fro.n  anterior  Horn  or  Cornu  of  Grey  Matter  m  the  Spinal 
Cord  of  a  CaJf"  l>,  Processes  ahroptly  broken  off.  a.  The  axis  eyhnder  proee.s. 
M.ijfnificd  al.nnt  SOO  .li.unacrs.     (Max  Hdn.lt/e.) 


CnAP.  II.]  A    NERVOUS    SYSTEM.  37 

cesses,'  whicli  are  either  much  branched  (fig.  12) 
(ramifymg  processes)  or  simple.  It  is  by  means  of  these 
different  kinds  of  processes  that  nerve  cells  are  united 
to  the  central  extremities  of  the  nerve  fibres  and  to  one 
another.  It  is  worthy  of  note  that  the  substance,  both  of 
the  nerve  cell  and  of  its  processes,  when  examined  under 
high  magnifying  powders  can  often  be  seen  to  be  dis- 
tinctly fibrillated  in  the  same  manner  as  the  '  axis  band  * 
of  a  nerve  fibre,  with  which,  or  with  the  ramifications  of 
which,  some  o^  these  processes  are  continuous. 

If  the  fibrillations  of  the  axis  band,  and  of  the  nerve 
process  into  which  it  may  be  continued,  correspond  with 
functionally  if  not  structurally  distinct  fibrils— that  is,  with 
separate  paths  for  stimulus  waves — so,  in  all  probability, 
the  fibrillations  of  the  nerve  cells  will  indicate  as  many 
distinct  paths  of  stimulus  waves  through  them  in  different 
directions.  The  appearances  presented  by  the  cells  are 
quite  consistent  with  this  view  (fig.  8).  Fibrillations,  for 
instance,  can  be  seen  passing  from  one  nerve  process 
in  a  curved  direction  through  the  body  of  the  cell  and  into 
another  process  ;  whilst  others  in  the  same  process  can  be 
followed  through  the  cell  in  quite  different  directions. 
There  is  no  difficulty  in  supposing  that  many  nerve  currents 
may  pass  through  one  of  these  compound  nerve  fibres, 
just  as  many  electric  currents  might  pass  simultaneously 
through  a  single  telegraphic  or  telephonic  wire. 

These  fibrillations  of  the  nerve  cell  are  probably  sequen- 
tial to,  and  gradually  differentiated  in  the  course  of,  its 
functional  activity.  It  is  not  unreasonable  to  expect  that 
there  would  be  a  gradual  marking  out  of  the  paths  of 
habitual  nerve  currents,  through  the  previously  structure- 
less though  slightly  granular  substance  of  the  nerve  cell, 
during  their  passage  from  fibre  to  cell  and  from  one  of 
these  bodies  to  another. 
3 


88  THE    STRUCTURE    OF 

In  accordance  with  this  view,  we  should  not  expect  to 
find  in  the  majority  of  ganglioD  cells  terminations  or  origins 
of  such  fibrils — whethei  in  the  nucleus  or  free  in  the  body 
of  the.  cell.  If  the  fibrillations  are  the  structural  correla- 
tives of  nerve  currents,  they  should  be  generally  as  con- 
tinuous and  unbroken  as  the  latter,  and  just  as  devious, 
winding  and  irregular  in  their  path. 

We  should  scarcely  look  for  free  ends  or  beginnings  to 
such  fibrils  elsewhere  than  at  the  periphery.  And  if  the 
semblance  of  free  ends  are  ever  recognizable  within  the 
body  of  the  cell,  it  will  probably/  be  in  young  cells  in 
which  the  functional  (and  therefore  the  structural)  current 
lines  have  not  yet  been  sufficiently  developed  by  constant 
repetitions.  Much  obscurity,  however,  still  reigns  in 
regard  to  all  these  matters.  We  do  not,  indeed,  know 
definitely  how  far  this  kind  of  fibrillation  of  the  nerve  cells 
is  general,  and  whether  there  may  not  be  whole  groups 
of  them  in  which  no  such  arrangement  exists.  It  is  quite 
conceivable  that  in  some  nerve  centres,  where  *  spon- 
taneity' of  action  appears  to  prevail  (or,  in  other  words, 
vrhence  widespread  and  sudden  irradiations  of  motor 
stimuli  may  emanate  on  slight  provocation),  we  might 
have  a  different  kind  of  action  altogether.  The  nerve 
cells  of  such  centres  may  approach  nearer  to  H.  Spencer's 
ideal,  and  be  true  '  libero-motor'  elements. 

The  Neuroglia,  or  intermediate  substance,  exists 
most  abundantly  in  the  larger  nerve  centres,  such  as  the 
Brain  and  Spinal  Cord.  It  has  been  most  commonly 
regarded  as  a  comparatively  insignificant  connective  tissue, 
though  some  few  physiologists  have  always  been  willing, 
and  even  anxious,  that  it  should  be  credited  with  higher 
developmental  and  functional  capacities. 

It  is  composed  in  part  of  minute  corpuscles  or  cells, 


Chap.  II.]  A  NERVOUS    SYSTEM.  39 

united  to  one  another  by  means  of  a  network   of  slender 
ramifying  fibrils  (fig.  9),  and  in  part  of  an  interspersed  homo- 
geneous or  simply  granular  basis  substance.     It  Las  been 
long  known  to  contain  some  small 
branched  corpuscles,  almost  indis- 
tinguishable    from     young    nerve 
cells ;     and    of     late    the    much 
branched  processes  of  many  fully 
developed   nerve    cells    have    also 
been  thought  to  have  a  structural 
continuity   with  this    minute  net- 
work of   the   neuroglia.      If  these 

.  .  Fig.  9.— Portion  of  Neuroglia 

observations    are  correct,  portions  from  the  spinai  cord.    Open 
01    the    'intermediate    substance'  ^^f"^  '^^"  ^,f'^  7^*\ '"f 

nuclei    or     cells     at     intervals, 

would   often  constitute    part    of   the    but  at  two  places  dose  lamein- 

...  T   ,  .       form  interlacements  are  shown. 

Circuits  traversed  by  nerve  currents  (Koiuker.)   Magnified  350  dia- 

in     their     passage     through     the  meters. 

centres. 

This  intermediate  tissue  is,  in  short,  the  probable  matrix 
wherein  and  from  which  new  nerve  fibres  and  new  nerve 
cells  are  evolved  in  animals,  of  whatsoever  kind  or  degree  of 
organization,  during  their  advance  in  reflex,  in  instinctive, 
or  in  intellectual  acquirements.  Some  such  process  must 
take  place,  pari  passu  with  the  acquisition  of  new  know- 
ledge and  powers,  of  all  kinds  and  howsoever  acquired : 
whether  it  comes,  as  in  lower  animals,  from  mere  intercourse 
with  natural  phenomena ;  or,  as  amongst  ourselves,  from 
similar  means,  supplemented  by  individual  application  in 
the  mastery  of  educational  or  professional  pursuits  and  of 
all  kinds  of  handiwork ;  or  whether  the  new  knowledge  and 
powers  come  to  us  as  a  result  of  that  more  general  edu- 
cation or  '  experience  '  which  is  gained  by  daily  intercourse 
with  the  pleasures,  troubles,  turmoils,  and  exertions  in- 
separable from  social  life.     The  acquirement  of  new  powers 


40  THE    STRUCTURE    OF 

or  accomplishments  must  correspond  either  with  more 
or  less  alteration  of  old,  or  with  the  development  of 
new  structures,  in  one  or  more  of  the  various  nerve 
centres. 


The  Structural  Relations  of  Nerve  Cells  with  Nerve 
Fibres,  and  with  one  another. 

Nerve  cells  are  supposed  to  communicate  with  nerve 
fibres  and  with  one  another  in  the  following  modes  ; — 

1.  The  nerve  cell  occurs  as  a  round  or  elongated  swell- 
ing in  the  course  of  a  nerve  fibre,  as  may  he  seen  in  figs. 
10  and  11. 

Here  an  undivided  nerve  fibre  sw^ells  more  or  less  abruptly 
into  the  nerve  cell,  and  similarly  emerges  therefrom,  so 
that  the  cell  in  this  case  is  only  a  nucleated  expansion  of 
the  fibre.  The  fibrils  of  the  axis  band  may  be  seen  pass- 
ing through  the  cell  in  a  divergent  and  re-convergent 
fashion,  having  the  finely  granular  basis  substance  of  the 
cell  between  them.  The  sheath  of  the  fibre,  though 
usually  not  the  medullary  substance  (fig.  10),  also  passes 
over  the  cell. 

A  point  which  will  be  found  more  doubtful  in  other  cases 
is  most  distinctly  illustrated  here  :  viz.,  that  a  struc- 
tural continuity  exists  between  the  substance  of  the  cell 
and  that  of  the  nerve  fibre.  There  is  no  distinct  line  of 
demarcation  between  the  two.  But,  so  far  as  we  know  at 
present,  this  particular  relation  of  fibre  and  eel]  exists 
principally  in  ganglia  peculiar  to  the  ingoing  ner  ves  and 
situated  near  the  great  centres  to  which  these  are  attached. 
There  is,  it  is  true,  some  reason  for  believing  that  a 
similar  relationship  may  exist  in  some  of  the  ganglia  on 


Chap.  IL] 


A    NERVOUS    SYSTEM. 


41 


Fig  10.— Three  bipolar  Ganglion  Cells  from  the  fifth  nerve  of  the  Pike  (Strieker 
after  Bidder). 

Fig.  11.— Three  bipolar  Ganglion  Cells  from  the  auditory  nerve  of  the  Pike  :  a. 
entirely  enclosed  within  the  medullary  sheath  ;  b,  entirely,  and  c,  partially,  exposed, 
to  show  that  these  ganglion  cells  are  only  expansions  of  the  axis  band. 


the  visceral  nerves,  and   tha-t  something  hke  it  also  exists, 


42 


THE    STRUCTURE    OF 


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0 

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Chap.  II.] 


A    NERVOUS    SYSTEM. 


48 


though  on  a  much  smaller  scale,  in  the  course  of  ultimate 
peripheral  nerve  fibres  (Beale). 

2.  The  ingoing  nerve  fibre,  on  subsequently  reaching  its 
centre,  divides  into  its  elementary  fibrils,  and  these  become 
structurally  continuous  with  a  fine  network  of  fibrils  (Ger- 
lach)  forming  the  rootlets 
of  ramifying  nerve  pro- 
cesses belonging  to  one 
or  more  contiguous  nerve 
cells  (fig.  1'2). 

This  kind  of  connec- 
tion is  thought  to  exist 
not  only  in  the  spinal 
cord,  but  also  in  the 
superficial  grey  matter 
of  the  brain  (both  cere- 
brum and  cerebellum), 
though  it  is  by  no 
means  certain  whether 
the  fibres  which  unite 
with  the  cells  in  this 
fashion  in  the  latter  or- 
gans constitute  ingoing 
or  outgoing  channels. 

It  is  into  such  a  union 
as  this  that  the  fibrils 
and  corpuscles  of  the 
*  neuroglia  '  (fig.  9) 
seem  to  enter.  Cer- 
tainly its  network  can- 
not be  distinguished  or 
clearly  separated,  in  many  nerve  centres,  from  that  formed 
by  the  ultimate  nerve  fibrils  and  the  branchlets  of  ramify- 
ing cell  processes. 


Fig.  13. —Multipolar  Ganglion  Cell  from  an- 
terior grey  matter  of  Spinal  Cord  of  Ox.  a, 
Axis  cylinder  process  ;  6,  branched  processes. 
Magnified  150  diameters.     (Ueiters. ) 


44  THE    STRUCTURE    OF 

3.  In  other  nerve  cells,  furnished  with  many  ramifying 
processes,  one  long  simple  process  maybe  seen  (figs.  13,  a, 
14),  which  is  occasionally  traceable  into  direct  continuity 
with  the  entire  axis  cylinder  of  a  nerve  fibre  (D(^iters). 
This  mode  of  union  is  now  generally  admitted  to  exist,  and 
it  is  not  improbable  that  nerves  so  arising  are,  usually  at 
least,  outgoing  fibres.  Whilst  this  view  cannot  be  defi- 
nitely verified,  it  is  a  fact  that  such  processes  have  been 
found  principally  in  the  spinal  cord  in  connection  with 
the  nerve  cells  of  the  anterior,  or  motor,  regions  of  its 
grey  matter. 

There  is  thus  some  ground  for  believing  that  ingoing 
fibres,  in  the  majority  of  cases,  swell  in  the  posterior  spinal 
ganglia  and  their  analogues  into  nerve  cells  (fig.  10) ; 
that  within  the  larger  nerve  centres  these  fibres,  which 
convey  ingoing  currents,  break  up  into  a  pencil  of  ultimate 
fibrils,  and  that  these  ultimate  fibrils  may  be  partly  in 
structural  continuity  with  the  neuroglia,  and  partly  with 
the  radicles  of  a  much  branched  nerve  process  (fig.  12), 
the  divisions  of  which  unite  (like  the  radicles  of  a  vein), 
till  they  are  gathered  into  one  or  more  branches  directly 
continuous  with  the  substance  of  the  nerve  cell.  Such 
arrangements  may  suffice  to  break  the  force  of  Ingoing  Cur- 
rents as  they  impinge  upon  highly  excitable  centres  ;  or 
their  diffusion  therein  may  thus  be  facilitated,  aud  as  a  con- 
sequence they  may  be  enabled  to  come  into  relation  with  the 
ultimate  ramifications  of  processes  pertaining  to  several  cells. 

On  the  other  hand,  there  is  ground  for  belioAdng  that 
Outgoing  Currents  leave  the  cells  of  the  spinal  motor 
centres  by  undivided  processes,  which  are  directly  con- 
tinuous with  the  axis-bands  of  dark  bordered  nerve  fibres. 

Should  these  su])p()sitions  be  correct  as  to  the  mode 
in  which  currents  impinge  upon  the  sensory  side,  and 
subsequently  issue  from  the  motor  side  of  a  nerve  centre, 


Chap.  II  ] 


A    NERVOUS    SYSTEM. 


45 


then,  ill  order  to  complete  our  mental  survey  of  the  path 
of  a  stimulus  wave  through  such  a  nervous  arc  as  is  called 
into  play  in  one  of  the  higher  animals  during  the  perform- 
ance of  a  *  reflex  ac- 
tion,' it  only  remains 
to  consider  the  modes 
of  connection  exist- 
ing between  the 
several  cells  of 
sensory  groups  and 
of  motor  groups, 
together  with  the 
kinds  of  communica- 
tion existing  between 
these  two  orders  of 
nerve  units. 

4.  Between  the 
contiguous  cells  of  a 
motor  and  perhaps 
also  of  a  sensory 
group,  union  is 
brought  about  in 
some  cases  by  means 

p               1       4-        •         1  ^'^^''  14.— Motor  Nerve  Cells  connected  by  inter- 

OI      a       SnOrtj      simple  cellular  processes  (6,  b),  and  giving  origin  to  outgo- 

intCi'CCllulctr  lirOCeSS  "^^  fibres  (c,  c,  c,  and  a).     4.  Multipolar  cell  contain- 

A                  '  ing  much  pigment  around  nucleus.     Diagrammatic. 

such  as  we  see  repre-  (Vogt.) 
sented  in  figs.  1  and 

14.  But  whether  this  is  the  most  frequent  means  of  union, 
or  whether,  in  the  majority  of  cases,  especially  amongst 
sensory  groups,  it  is  not  rather  by  the  inosculation  of  the 
rootlets  of  ramifying  processes  (with  the  possible  interme- 
diation of  the  neuroglia)  we  cannot  at  present  say.  There 
is  reason  to  believe  that  both  modes  of  union  may  exist. 

5.  The  cells  of  a  sensory   group   are  united  with  the 


46 


THE    STRUCTURE    OF 


cells  of  a  motor  group  by  one  or  other  of  these  modes — 
though  in  regard  to  this  point  we  have  even  less  certain 
knowledge  than  concerning  the  last.  Of  the  existence 
of  such  connecting  or  *  commissural '  fibres — ^which  are 
either  short  or  long  according  to  the  proximity  or  re- 
moteness of  the  two  gi-oups  of 
cells — there  can  be  no  doubt. 
Uncertainty  exists,  however,  with 
regard  to  the  precise  mode  of  their 
connection  with  the  sensory  nerve 
cells  on  the  one  side  and  the 
motor  on  the  other — whether  at 
either  extremity  they  are  continu- 
ous with  undivided  cell-processes, 
or  break  up  and  inosculate  with 
ramifying  cell-processes. 

More  room  for  doubt,  therefore, 
exists  in  regard  to  the  precise 
modes  in  wdiich  stimulus  waves 
traverse  nerve  centres,  than  con- 
cerning the  manner  in  which  they 
impinge  upon  or  depart  there- 
from. 

6.  In  the  '  sympathetic '  or  vis- 
ceral ganglia  of  the  Frog  and  other 
animals  another  kind  of  relation 
between  fibres  and  cells  has  been 
shown  to  exist  (Lionel  Beale). 
Fifi.  15. -'Sympathetic'  Gan-  The  cclls  are  pcar-sliapcd  and  the 

glioii-cell  of    a   Frog,  very  higlily  .  n  ^        r    ^ 

magnified  ;    according    to    Beale.  naiTOW  extremity  01  Cacll  01  them 

Keduced  and  adapted  from  one  of  j^  continued  iuto  a   prOCCSS  which 
his  figin-es.  a  a,  straight  nhre  ;  0  o,  -t 

coiled  fibre  ;  c,  smaller  one  joining  in    tum  bcCOmCS  COlltinUOUS  witll 

a  dark-bordered  fibre,  whilst  one 
or,  it  may  be,  two  or  more  smaller  fibres  seem  to  arise  from 


Chap.  II  ] 


A    NERVOUS    SYSTEM. 


47 


the  surface  substance  of  the  same  extremity  of  the  cell, 
whence,  after  twisting  round  it  and  the  straight  process 
several  times,  they  pass  away  in  difterent  directions. 
Occasionally  L.  Beale  has  seen  the  spiral  process  con- 
tinuous with  a  dark-bordered  fibre,  though  in  such  cases 
it  is  not  certain  whether  the  straight  process  is  or  is  not 
continuous  with  a  fibre  of  the  same  kind.  J.  Arnold  has 
also  described  cells  of  this  type,  and  believes  that  the  pro- 
cesses are  in  connection  with  the  nucleus  of  the  cell,  an 
arrangement  which  has  not  been  .confirmed  by  other 
observers.  The  fig- 
ures given  by  Axel 
Key  and  Retzius 
agree  closely  with 
those  of  Beale. 

7.  But  in  the 
*  sympathetic  '  or 
visceral  ganglia  of 
man  and  other 
higher  vertebrates  it 
is  most  common  to 
find  many  simple 
processes  issuing 
from  large  and  very 
granular  ganglion 
cells.  Whether 
each  is  directly  con- 
tinuous witha  single 
nerve  fibre,  after  the 
fashion  diagramma- 
tically  depicted  in 
fig.    2,    or  whether 

some  of  the  processes  end  differently,  has  not  as  yet  been 
sufficiently  ascertained.     These  large  multipolar  ganglion 


Fig.  16.— Multipolar  Ganglion- cells  from  'Sympa- 
thetic' of  Man  (Max  Schultze  .  Highly  magnified,  r', 
freed  from  capsule  ;  b,  enclosed  within  nucleated  cap- 
sule.    The  processes  of  both  broken  off. 


48  THE    STRUCTURE    OF 

cells  of  the  sympathetic,  like  those  last  descrihed,  are 
enveloped  by  a  fine  membranous  sheath  dotted  with  many 
nuclei,  and  the  sheath  is  continued  for  some  distance 
along  each  of  the  nerve  processes,  in  the  form  of  a  loose 
envelope. 

8.  Lastly,  unipolar  nerve  cells — that  is,  nerve  cells 
situated  at  the  end  of  a  single  nerve  fibre—  are  alleged  to 
exist  in  the  ganglia  on  the  spinal  nerves  and  elsewhere. 
1  Ley  have  again  recently  been  figured  by  Axel  Key  and 
Betzius,  though  many  modern  observers  have  been  very 
sceptical  as  to  the  existence  of  such  bodies.  Beale,  for 
instance,  maintains  that  all  nerve  cells  have  at  least  two 
processes.  Without  attempting  to  explain  their  use  or 
mode  of  action,  it  seems  to  the  writer  that  such  unipolar 
nerve  cells  certainly  exist  in  some  of  the  lower  animals. 
He  has  himself  seen  and  figured  such  bodies  as  they  occur 
in  Ascaris  (Phil.  Trans.  1866,  PI.  xxiv.)  ;  and  in  many 
other  animals  nerve  units  of  the  same  kind  have  been 
likewise  recognized  by  competent  observers. 

Many  of  the  so  called  apolar  nerve  cells  may,  as 
G.  H.  Lewes  suggests  in  a  recent  work,*  be  nothing 
more  than  imperfectly  developed  ganglion  cells,  in  which 
the  processes,  if  not  absent,  are  so  abortive  as  to  escape 
observation.  All  who  have  examined  nerve  centres  with  the 
microscope  know  that  multitudes  of  such  bodies  are  to  be 
found,  though  they  are  often  very  small — not  much  larger 
than  mere  nuclei — and  therefore  liable  to  be  regarded  as 
belonging  to  the  neuroglia  rather  than  to  the  nervous 
tissue  proper.  And  if  some  of  the  cells  and  nuclei  usually 
assigned  to  the  'neuroglia'  are,  in  reality,  potential  or 
embryo  nerve  cells,  the  importance  of  this  intermediate 
tissue  as  a  formative  matrix  in  which  new  developments 
may  take  place,  will  at  once  appear. 

*  "  Tlic  i'h^.sical  Basis  oi"  Mind,"  1877,  p.  234. 


Chap.  II.] 


A    NERVOUS    SYSTEM. 


49 


Thus  far  concerning  the  simplest  elements  of  a  nervous 
mechanism.  It  f-houkl  now  be  stated,  however,  that  even 
when  the  Nervous  System  consists  of  a  mere  multiplication 
of  the  simplest  combinations  necessary  for  the  excitement 
and  execution  of  '  reflex  actions,'  the  groups  of  these 
nervous  arcs  are  almost  always  arranged  in  pairs,  one  on 
each  side  of  the  middle  line  of  the  body.  The  body  of  an 
animal  is  for  the  most  part  divisible  by  a  median  longi- 
tudinal plane  into  two  symmetrical  halves,  and  the  integral 
parts  of  the  nervous  system  are,  in  the  main,  similarly 
double.  In  some  lower  organisms,  such  as  certain  MoUusks, 
Worms,  and  Crustacea,  these  halves  of  the  nervous  system 
are  distinctly  separated  from  one  another  (figs.  23,  32, 
34),  though  in  Vertebrate  Animals  they  are  always  more  or 
less  fused  into  one  axial  '  cerebro-spinal  '  system  (fig.  20), 


Pio.  17  —Nervous  System  of  one  of  the  Eolidfe  (Fiona  ailantkci).  (Gegenbauer  after 
R.  Bergh).  A,  Suprd-resophageal  sensory  ganglia,  composed  of  two  pairs  of  ganglia 
fused,  the  cerebral  in  front  and  the  branchial  behind  ;  each  pair  united  by  its  own 
commissure.  B,  Great  motor  ganglia,  in  connection  with  the  sensory  ganglia,  and 
with  one  another  by  the  commissui-e  e.  (J,  Buccal  ganglia.  D,  Gastro  oesophageal 
ganglia,  a  and  b.  Nerves  from  the  sensory  tentacles,  c.  Nerves  from  the  genital 
organs,  d,  Principal  motor  nerves  of  the  body,  t',  Commissure  of  the  branchial 
ganglia. 

These  lateral  halves  of  the  nervous  system  are  connected 
wit-h  one  another  by  means  of  shorter  or  longer  transverse 
fibres,  which,  gathered  into   thick   or  thin  bundles,   arc 


50  THE    STRUCTURE    OF 

known  as  *  commissures.'  Such  transverse  commissures 
always  unite  similar  ganglia,  whether  these  are  so  close 
as  to  be  more  or  less  continuous,  or  distinctly  separated 
from  one  another.  Two  or  three  illustrations  will  suffice 
to  make  these  bilateral  arrangements  more  intelligible  to 
the  reader. 

In  some  of  the  Nudibranchiate  Mollusks  so  common  on 
the  sea- shore,  there  is  in  front  and  on  each  side  a  large 
roundish  though  functionally  compound  ganglion  receiving 
numerous  ingoing  nerves  and  connected  with  its  fellow 
by  means  of  a  very  thick  and  a  thin  commissure  (fig.  17). 
The  sensory  ganglion  is  also  connected  on  each  side  by 
means  of  a  short  commissure  with  its  own  motor  ganglion, 
from  which  outgoing  nerves  proceed  to  the  muscles,  and 
the  two  motor  ganglia  are  in  their  turn  connected  by  a 
longer  transverse  commissure  (fig.  17,  e). 

Thus,  in  each  half  of  the  body  of  one  of  these  ani- 
mals there  is  a  complex  aggregate  of  the  mechanisms  for 
reflex  actions — represented  by  ingoing  fibres  entering  a 
sensory  ganglion  in  connection  with  a  motor  ganglion, 
together  with  outgoing  fibres  issuing  from  the  latter. 
Whilst  in  addition,  the  two  halves  of  the  nervous  system 
are  united  to  one  another  by  the  above-mentioned  trans- 
verse commissures.  It  is  by  virtue  of  these  connections 
between  the  respective  ganglia  of  the  two  sides  that  a 
properly  co-ordinated  activity  of  the  whole  body  is  rendered 
possible,  in  response  to  sensory  stimuli. 

In  other  animals,  such  as  the  Grasshopper,  whilst  the 
bilateral  symmetry  of  the  nervous  system  (fig.  18)  is  just 
as  obvious,  it  is  much  more  complex  and  more  developed 
longitudinally.  The  sensory  and  motor  ganglia  are  nume- 
rous and  are  arranged  side  by  side  in  serial  order,  though 
many  of  them  are  more  completely  fused  with  one  another 
and  with  those  of  the  opposite  side  than  is  the  case  with 


Chap.  II.] 


A    NERVOUS    SYSTEM. 


51 


the  two  pairs  of  gan- 
glia of  Eolis.  Thus 
median  compound 
ganglia  (fig,  18,  g) 
are  formed,  connected 
with  one  another  by 
single,  or  it  may  be 
by  double  (<?,  //)  com- 
missures. The  ter- 
minal double  group 
(a)  represents  the 
brain  of  the  animal, 
and  this  is  probably 
capable  of  receiving 
stimuli  by  some  fibres 
from  the  sensory  por- 
tion of  each  single  or 
double  ganglion 
throughout  the  body 
of  the  Insect.  It  can 
probably  also  transmit 
motor  stimuli  along 
other  commissural 
fibres  to  each  motor 
division  of  the  same 
body  ganglia. 

In  the  Grasshopper 
the  brain  is  not  m.ore 
than  three  or  four 
times  as  large  as  one 

of  the  compound  gan-  ^^^^  is.-Xervous  system  of  the  Great  Green 
glia  in  communication  Grasshopper  (Newport).  A,  brain  ;  B,  optic  nerves ; 
D,  antisnnal  nerves  ;  d,  motor  nerve  of  mandible 
from  sub-oesopbageal  ganglion  ;  [/,  first  thoracic  gan- 
glion, connected  to  the  second,  as  the  second  is  to 
*^    *  ,       the  third,  by  two  commissures. 

In  Vertebrate  Ani- 


with    the 
winffs. 


legs 


and 


52 


THE    STRUCTURE    OF 


mals  we  have  a  still  farther  concentration  of  the  nervous 
system.  In  lower  terms  of  the  series,  such  as  Fishes 
and  Amphibia  (fig.  56),  this  concentration  is  seen  to  the 
most  marked  extent  in  the  chain  of  ganglia  pertaining 
to  the  thorax  and  abdomen.  In  these  animals  and  in 
all  other  vertebrates  they  are  most  completely  fused  into 


uikn  U! 


Fig.  19.— Transverse  section  through  Iliiman  Spinal  Cord  in  cervical  region, 
showing  the  organ  to  he  composed  of  two  symmetrical  halves.  (Sappey  after  Stilling.) 
The  black  portions  orrespoud  to  regions  containing  longitudinal  fibres  ;  the  lighter 
portions  represent  the  central  Grey  Matter  and  the  horizontal  roots  of  nerves ; 
5,  6,  commissu  es  connecting  the  symmetrical  halves  of  the  grey  matter  ;  11,  11, 
11  antcri'  ror  motor  roots  of  spii  al  nerves,  coming  from  anterior  Horns  or  Cornua 
of  Grey  Matter,  in  which  are  mnnt-rous  groiiiw  of  large  ganglion  cells;  LS,  pos- 
terior or  sens.  )ry  roots  of  spinal  nerves,  entering  the  posterior  Horns  of  Grey  Matter. 
Magnified  about  eight  diameters. 


a  more  or  less  cylindrical  column  known  as  the  '  spinal 
cord.'  This  cord  constitutes  a  double  and  fused  series 
of  nerve  centres  in  relation  with  the  superficial  as  well  as 
with  the  deeper  structures  of  the  greater  part  of  the  body, 
including  all  the  great  nerves  of  the  limbs. 


Chap.  II.] 


A    NERVOUS    SYSTEM. 


53 


In  higher  ver- 
tehrates,  such  as 
Birds  and  Mam- 
mals, we  have  this 
same  fusion  of  gan- 
glia in  the  spinal 
cord  (fig.  19),  whilst 
a  similar  process 
also  displays  it- 
self to  a  more 
marked  extent  in 
the  brain.  In  the 
higher  forms  of 
this  series,  and 
above  all  in  Man 
himself,  the  gan- 
glia of  the  brain 
become  more  and 
more  integrated, 
and  some  of  these 
parts  also  take 
on  an  enormous 
development. 

The  weight  of 
the  entire  Brain, 
as  compared  with 
that  of  the  Spinal 

Cord     indeed      Un-         ^^^'  20.— General  view  of  Nervous  System  of  Man,  from 
'  '      .  behind.      1,  Cerebi'um  ;  2,  cerebellum  ;  3,  upper  part  of 

dergoes  a  great  in-    spiuaicord.   (Mivart.) 
crease  in  each  divi- 
sion of  the  vertebrates.     In  the  Lamprey  this  relation  is 
said*  to  be  as  'OlS  to  1 ;  in  the  Newt  as  '55  to  1;   in  the 
Pigeon  as  3*5  to   1 ;  in  the  Mouse  as  4  to  1  ;  whilst  in 
*  Marshall's  "  Outlines  of  Physiology,"  vol.  i.  p.  406. 


54  THE    STRUCTURE   OF    A    NERVOUS    SYSTEM. 

Man  it  is  about  40  to  1.  Thus,  whilst  the  Cerebrum 
and  the  Cerebellum,  which  together  constitute  the  Brain, 
is  actually  much  lighter  in  the  Lamprey  than  the  Spinal 
Cord,  these  same  parts  in  Man  are  found  to  attain  com- 
paratively enormous  dimensions,  and  greatly  to  exceed  in 
weight  the  inferior,  though  highly  important,  spinal 
centres. 


CHAPTEK  in. 

THE  USE  AND  NATURE  OF  SENSE  ORGANS. 

Heat  and  light  are  physical  influences  to  which  even 
the  lowest  units  of  living  matter  respond,  whether  their 
mode  of  life  and  nutrition  be  most  akin  to  that  of  Plants 
or  to  that  of  Animals.  These  influences  act  upon  such 
organisms,  either  by  stimulating,  retarding,  or  otherwise 
modifying  the  chemical  changes  occurring  in  their  interior, 
and  upon  the  existence  of  which  their  Life  depends. 

Where  the  vital  processes  of  the  organism  are  stimulated 
by  these  physical  agencies,  their  incidence  may,  in  many 
instances,  become  the  cause  of  so-called  *  spontaneous  * 
movements.  And  some  sort  of  foundation  exists  for  this 
popular  mode  of  expression.  A  movement  which  follows 
immediately  upon  some  localized  external  stimulus  is 
not  said  to  be  *  spontaneous : '  the  term  is  generally 
applied  where  the  cause  of  the  movement  is  not  distinctly 
recognizable.  In  some  of  these  cases — as  when  we  have 
to  do  with  the  influence  of  a  diffused  physical  agent  such 
as  heat — an  undetected  or  unconsidered  external  cause 
really  exists,  which,  by  stimulating  the  vital  processes, 
gives  rise  to  movements  seemingly  spontaneous.  Whilst  in 
other  cases,  movements  apparently  spontaneous  are  to 
be  referred  to  internal  states  or  changes,  that  is  to  impres- 
sions emanating  from  some  of  the  internal  organs  which, 
after   passing  through  one  or  more  ganglia,  are   trans- 


56  THE    USE    AND   NATURE 

mitted  along  outgoing  nerves  to  some  of  the  organs  of 
locomotion. 

Heat  often  acts  upon  organisms  upon  all  sides  alike ; 
consequently,  though  it  maj^  stimulate  their  life-processes 
generally  and,  in  some  instances,  give  rise  to  movements 
— the  latter  are  not  determined  in  one  more  than  in  an- 
other direction.  It  is  well  known  to  stimulate  the  *  to- 
and-fro  '  or  the  gyratory  movements  of  Bacteria,  and  other 
of  the  lowest  organisms ;  and  whilst  it  also  renders  more 
striking  and  rapid  those  changes  of  form  which  all  Amoe- 
boid Organisms  are  apt  to  display,  the  movements  evoked 
are  similarly  random  and  devoid  of  purpose. 

It  is  not  altogether  similar  with  the  influence  of  Light. 
This  agent  almost  always,  and  of  necessity,  falls-  more  on 
one  side  of  an  organism.  Consequently  it  often  suffices 
to  induce  movements  of  the  lower  forms  of  life  in  definite 
directions,  just  as  it  causes  similar  responsive  movements 
to  be  executed  by  the  parts  of  any  higher  plants  which  may 
come  fully  under  its  influence.  In  each  case  the  move- 
ment, or  altered  position,  is  due  to  some  nutritive  change — 
that  is,  to  some  alteration,  whatever  its  nature,  in  the 
activity  of  the  life-processes  taking  place  in  the  part 
impressed  by  the  light.  So  that,  whether  we  have  to  do 
with  the  movement  of  a  Sunflower  or  with  the  loco- 
motions of  minute  living  units,  the  essential  mode  of 
production  of  the  movement  is  probably  similar. 

Of  such  locomotions  of  minute  living  organisms  under 
the  influence  of  light  many  instances  might  be  cited ;  it 
will  suffice,  however,  to  mention  the  fact  that  green 
Zoospores,  which  may  have  been  uniformly  diffused 
through  the  water,  are  very  apt,  when  the  vessel  containing 
them  is  placed  near  a  window,  to  collect  on  the  surface  of 
the  water  at  tli5  part  where  most  light  falls,  and  the  same 
would  hold  good  also  for  many  Medusas.     Minute  animal 


Chap.  III.]  OF    SENSE    ORGANS.  67 

organisms  are,  however,  often  affected  quite  differently  by 
this  agent.  They  may  move  away  from  rather  than 
towards  its  source,  and  to  this  extent  may  be  said  to 
'  seek '  the  shade  rather  than  the  glare  of  sunlight. 

The  operation  of  such  influences  and  their  results, 
form  the  beginnings  or  substrata,  as  it  were,  of  other 
phenomena  with  which  we  are  now  more  particularly 
concerned.  The  unilateral  influence  of  Light  and  the 
movements  to  or  from  its  source  to  which  it  gives  rise, 
afford  a  connecting  link  between  diffused  causes  like 
Heat,  which  operate  generally  and  produce  purely  random 
motions,  and  those  more  localized  influences  now  to  be 
considered,  by  which,  and  the  intermediation  of  a  more 
and  more  complex  Nervous  System,  the  various  definite 
or  responsive  movements  of  organisms  have  been  gradually 
evoked  and  potentially  organized. 

Touch. — The  first  to  be  considered — ^because  it  is  the 
simplest — of  these  localized  influences,  is  a  shock  on  me- 
chanical impact  of  some  kind  falling  upon  the  external 
surface  of  the  organism.  This  is  the  primordial  and  most 
general  of  all  the  modes  by  which  the  surface  of  an 
organism  is  impressible.  Its  sensitivity  to  such  stimuli 
is — both  in  the  stage  of  impression  and  in  that  of 
reaction — closely  akin  to  the  general  organic  irritability  of 
protoplasm,  which  unquestionably  constitutes  its  starting 
point.  These  modes  of  impression  and  reaction  are  the 
first  links  towards  the  establishment  of  a  correspondence 
between  the  organism  and  the  most  common  events  or 
properties  of  the  mediam  in  which  it  lives  and  moves. 
It  is,  consequently,  the  kind  of  impressibility  most  exten- 
sively called  into  play  in  all  the  lower  forms  of  animal 
Ufe. 

Although  the  whole  or  the  greater  part  of  the  surface  of 


58  THE   USE   AND    NATURE 

an  organism,  in  one  of  the  simple  animals  to  which  we 
are  referring,  may  be  more  or  less  impressible  to  shocks  or 
impacts  from  contact  with  surrounding  bodies,  it  often 
happens  that  such  impressions  more  frequently  fall  upon, 
and  are  more  readily  received  by,  certain  appendages 
situated  at  the  anterior  extremity  of  the  animal,  in  close 
proximity  to  the  mouth.  These  specialized  parts,  or 
*  tactile  appendages',  are  known  as  papillae,  setae,  tentacles, 
antennae,  or  palpi,  according  to  the  forms  which  they 
assume  in  different  animals. 

Why  such  organs  should  be  developed  so  frequently  at 
the  anterior  extremity  of  the  animal,  and  in  the  neigh- 
bourhood of  the  mouth  rather  than  on  other  parts  of  the 
body,  is  not  difficult  to  explain.  Whatever  the  mode  by 
which  they  are  called  into  being  (and  the  most  opposite 
views  are  entertained  upon  this  subject),  it  seems  obvious 
that,  if  organs  of  this  nature  are  to  be  present  at  all, 
they  should  be  found  in  situations  where  they  may  be 
put  to  most  use.  In  an  animal  accustomed  to  active 
locomotions,  the  mouth  is,  with  only  a  very  few  excep- 
tions, situated  on  the  part  of  the  body  which  is  habitu- 
ally directed  forward.  And  of  the  diverse  objects  coming 
into  contact  with  it,  some  are  of  a  nature  to  serve  as  food, 
and  some  are  not.  A  high  degree  of  impressibility  natu- 
rally becomes  developed,  therefore,  in  this  situation, 
where  the  parts  are  exercised  so  largely  with  impressions 
connected  with  the  discrimination  and  capture  of  food. 
These  organs  are,  in  fact,  not  unfrequently  both  tactile 
and  prehensile — this  combination  being  more  especially 
met  with  in  sedentary  forms  of  life,  like  the  Hydra,  the 
Sea-anemone,  or  some  of  the  tentaculated  Worms. 

Taste. — But  it  often  happens  that  the  solid  bodies 
serving  as  food  are  more  or  less  readily  soluble,  so  that  in 
animal  organisms  comparatively  low  in  the  scale  of  com- 


Chap   III.]  OF   SENSE    ORGANS.  59 

plexity,  some  of  the  tactile  structures  within  or  around 
the  mouth  may  undergo  a  further  speciaHzation,  by  which 
they  and  their  related  nerve  centres  become  fitted  to  dis- 
criminate between  impressions  of  a  slightly  different 
nature.  Such  '  organs  of  taste  '  would  become  sensitive 
to  the  more  refined  kind  of  contact  yielded  by  certain 
dissolved  elements  of  the  food,  whose  local  action  is 
perhaps  attended  by  some  slight  chemical  change  in  the 
tissues  of  the  part.  Impressions  are  thus  produced 
whereby  the  '  sapidity '  or  flavour  of  bodies  is  appreciated ; 
and  such  impressions  gradually  become  associated  with 
definite  related  movements,  partly  of  internal  and  partly  of 
external  organs. 

Although  this  mode  of  impressibility  doubtless  exists 
in  many  of  the  lower  forms  of  life,  still  no  distinct  organ 
of  Taste,  or  specialized  gustatory  surface,  is  as  yet  actually 
known  to  occur  among  invertebrate  animals,  except  in 
Insects  and  in  such  higher  mollusca  as  Snails  and  Cuttle- 
fishes. 

Impressions  of  the  two  orders  already  referred  to — 
more  or  less  distinct  from  one  another — are  those  by 
which  alone  multitudes  of  the  lower  forms  of  animal  life, 
such  as  Polyps  and  various  kinds  of  Worms,  appear  to 
hold  converse  with  the  outside  world.  Seeing,  however, 
that  tactile  and  gustatory  impressions  can  only  be  made  by 
actual  contact  of  external  bodies  with  the  specialized  parts 
of  an  organism,  such  impressions  are  not  of  a  kind  to 
excite  movements  in  '  quest  *  of  food ;  although  they  may 
lead  to  correlated  motions  of  parts  adjacent  to  those 
touched,  as  in  the  acts  of  prehension  and  swallowing. 

Sight. — Movements  in  actual  quest  of  food  may,  how- 
ever, be  excited  in  other  animal  organisms  by  impressions 
bringing  them  into  relation  with  more  or  less  distant 
bodies.      The  way  is  paved  for  this  result  when  some 


60  THE    USE    AND    NATURE 

portion  of  the  anterior  and  upper  surface  of  the  animal, 
in  which  aggregations  of  pigment  ocsar,  becomes  more 
than  usually  sensitive  to  light.  A  dark  body  passing  in 
front  of  such  a  region  alters  or  gives  rise  to  certain 
molecular  changes  therein,  and  these  molecular  changes 
(produced  by  large  or  small,  near  or  remote,  bodies) 
differing  among  themselves,  become  capable  of  exciting 
dissimilar  impressions  which  the  organism  is  gradually 
attuned  to  discriminate.  The  existence  of  such  a  power 
of  discrimination  in  this,  as  in  all  other  like  cases,  is 
indicated  by  the  creature's  capability  of  responding  to 
impressions  of  this  order  by  definite  muscular  movements 
— as  when  the  Oyster,  having  the  valves  of  its  shell 
apart,  instantly  closes  them  as  soon  as  a  shadow  falls  upon 
certain  pigment- specks,  or  so-called  '  eyes,'  at  the  edge  of 
its  mantle.* 

This  beginning  of  visual  impressions  truly  enough  shows 
itself  as  a  very  exalted  appreciation  of  tactile  impressions  ; 
and,  inasmuch  as  such  an  appreciation  of  the  presence 
of  near  bodies  would  in  so  many  instances  be  quickly 
followed  by  a  more  gross  mechanical  contact,  the  rudimen- 
tary visual  impression  is,  as  H.  Spencer  happily  puts  it,  a 
kind  of  "anticipatory  touch."  From  a  simple  beginning 
of  this  kind,  in  which  bodies  only  slightly  separated  from 
the  impressible  foci  excite  certain  general  or  only  vaguely 
specialized  impressions  corresponding  to  light  and  shade, 
organs  of  Sight  at  once  more  elaborate  and  more  impres- 
sible gradually  appear.  To  rudimentary  aggregations  of 
pigment,  in  some  animals  transparent  media  are  added, 

*  Owen  says  ('*  Comp.  Anat.  of  the  Invert.  Animals,"  p.  512): — 
"Carlisle  first  sliowetl  tluit  oysters  were  sensible  of  liglit ;  having 
observed  that  they  closed  their  valves  when  the  shadow  of  aa 
approaching  boat  was  thrown  forwards  so  as  to  cover  them,  before 
any  undulation  of  the  water  could  have  reached  them." 


Chap.  III.]  OF    SENSE   ORGANS.  61 

serving  to  condense  the  light  thereon ;  and  these  media 
in    still  other  organisms  are   sufficiently  like   a  lens   to 
be  adequate  to  form  a  definite  image  of  an  external  body 
on  the  layer  of  pigment,  which  (on  its  other  side)  is  in 
contact  with  a  nerve-expansion  directly  communicating 
with  a  contiguous  ganglion.     Numerous  simple  structures 
of  this  kind  may  exist  apart  from  one  another,  as  in  many 
Bivalve  Mollusks ;  or  they  may  be  far  more  numerous  and 
closely  aggregated,  so  as  to  form  such   compound-eyes  as 
are  met  with  in  Crustacea  and  in  Insects.     Or  individual 
ocelli  may  be  perfected,  as  in   Spiders  or  lower  Crustacea, 
and   most  notably  of  all  among  the  Cuttlefish  tribe,  in 
the  representatives  of  which  two  moveable  eyes  are  met 
with  whose  organization  is  just  as  perfect  as  those  of  Fishes. 
The   difference   in  degree  and  range  of    sensitiveness 
between  the  simple   '  eye- specks  '  of   some  of  the  lower 
Worms,   and  the  elaborate  visual  organs  of  the  highest 
Mollusks  and  Insects  is  enormous.     The  range  and  keen- 
ness of  sight  also  become  progressively  extended,  so  that 
creatures   with    the    more    perfect   eyes    are   capable   of 
appreciating   impressions   from    objects   more   and  more 
distant,  and  the  various  actions  which  become  established 
in  response  to  impressions  habitually  made   upon  such 
sensitive   surfaces  also   increase  enormously  in   number, 
variety,  and  complexity.     The  relation  between  the  keen- 
ness of  the  sense  of  sight  and  the   great  powers  of  loco- 
motion possessed  by  Insects  has  long  been  recognized  by 
naturalists.     Prof.  Owen  thus  alludes  to  it:  "The  high 
degree  in  which  the  power  of  discerning  distant  objects  is 
enjoyed  by  the  flying  insects  corresponds  with  their  great 
power  of  traversing  space.     The  few  exceptional  cases  of 
blind  insects  are  all  apterous,  and  often  peculiar  to  the 
female  sex,  as  in  the  Glow-worm,  Cochineal-insect,  and 
parasitic  Styiops." 
'  4 


62  THE    USE    AND    NATUllE 

As  already  pointed  out,  there  are  obvious  reasons  why 
the  principal  specialized  Tactile  Organs  that  may  present 
themselves  in  lower  animals,  should  be  found  in  the 
neighbourhood  of  the  mouth  ;  and,  for  similar  reasons,  if 
for  no  other,  the  anterior  extremity  of  the  body,  or  the 
upper  surface  near  this  anterior  extremity,  is  the  most 
advantageous  site  for  Visual  Organs.  To  an  active  animal, 
eyes  would  not  only  be  more  useful  at  the  anterior 
extremity  of  the  body  than  elsewhere,  in  relation  to  its 
food-taking  movements,  but  also  in  reference  to  all 
other  uses  to  which  such  organs  may  be  applied  during 
active  locomotions  from  place  to  place.  And  to  this 
situation  of  the  eyes  only  two  or  three  exceptions  are  met 
with  among  animals  endowed  with  powers  of  locomotion : 
whilst  the  few  cases  of  deviation  are  mostly  explicable  by 
reference  to  some  peculiarity  in  the  habits  and  modes  of 
life  of  the  organisms  in  question. 

Smell. — In  vision,  as  above  stated,  we  have  to  do  with 
a  refinement  of  the  sense  of  touch,  whereby  the  animal, 
becoming  sensible  of  impressions  produced  by  '  waves '  of 
light  emanating  from  a  distance,  is  brought  into  mediate 
contact  with  certain  distant  objects.  But  a  sort  of  refine- 
ment of  the  organs  of  taste  also  occurs,  whereby  bodies 
possessing  sapid  and  other  qualities  are  also  capable  of 
impressing  organisms  still  at  a  distance.  Just  as  vision 
is,  in  its  most  elementary  phases,  a  sort  of  anticipatory 
touch,  so  is  smell  a  kind  of  anticipatory  taste.  Yet  the 
two  cases  are  not  altogether  similar.  In  vision,  the 
contact — if  it  may  be  so  termed — with  the  distant 
body  is  mediate,  through  the  intervention  of  ethereal 
undulations ;  whilst  in  smell  we  have  to  do  with  a  case 
of  immediate  contact,  not,  of  course,  with  the  distant 
body  itself,  but  with  extremely  minute  particles  which 
it  gives   off.     An    '  emission  '    theory  serves   to    explain 


Chah.  in.]  OF    SENSE    ORGANS.  63 

the  diffusion  of  odours,  though  it  will  not  hold  for  tho 
diffusion  of  light. 

From  what  I  have  said,  it  ma}^  be  inferred  that,  as  re- 
gards the  delicacy  of  their  respective  physical  causes,  the 
sense  of  Smell  occupies  a  strictly  intermediate  position 
between  those  of  Taste  and  Sight. 

Although  a  rudimentary  sense  of  Smell  seems  unques- 
tionably to  be  possessed  by  such  aquatic  forms  of  the 
invertebrata  as  Crustacea  and  the  higher  Mollusks,  it  is, 
perhaps,  a  sense-endowment  which  generally  exists  to  a 
more  developed  and  varied  extent  amongst  air-breathing 
animals.  But  in  whatever  forms  of  life  it  may  be  met 
with,  this  sense-endowment  seems  to  be  always  very 
largely  related  to  the  detection  and  capture  of  food.  In 
this  direction  it  comes  to  the  aid  of  the  already  existing 
senses  of  Sight,  Touch,  and  Taste.  It  has,  however,  the 
peculiarity  of  being  scarcely  otherwise  called  into 
activity  amongst  invertebrate  animals. 

Although  we  have  so  little  positive  knowledge  con- 
cerning the  situations  of  Organs  of  Smell  in  invertebrates, 
there  is  good  reason  for  believing  that  they  will  (when 
present)  always  exist  in  close  proximity  to  the  mouth. 
It  seems  possible  that  in  Crustacea  they  are  to  be  found 
at  the  base  of  the  antennules;  that  in  Cephalopods  they  are 
represented  by  two  little  fossae  in  the  neighbourhood  of 
the  eyes  ;  and  that  in  Insects  a  power  of  appreciating 
odours  may  be  possessed  either  by  the  antennae  them- 
selves, or  by  a  pair  of  fossae  near  their  bases.  Another 
cephalic  organ  has  also  been  referred  to  as  possibly  en- 
dowed with  a  power  of  being  impressed  by  odours.  Owen 
says  :*  "  The  application  by  the  common  house-fly  of  the 
sheath  of  its  proboscis  to  particles  of  solid  or  liquid  food 
before  it  imbibes  them,  is  an  action  closely  analogous  to 
*  "Coiiip.  Aiiat.  of  Invertebrate  Animals,"  p.  oG8. 


64  THE    USE    AND    NATURE 

the  scenting  of  food  by  the  nose  in  higher  animals ;  and, 
as  it  is  by  tlie  odorous  qualities,  much  more  than  by  the 
form  of  the  surface,  that  we  judge  of  the  fitness  of  sub- 
stances for  food,  it  is  more  reasonable  to  conclude  that, 
in  this  well-known  action  of  our  commonest  insect,  it  is 
scenting,  not  feeling,  the  drop  of  milk  or  grain  of  sugar." 

The  part  of  the  body  bearing  the  mouth  and  the  various 
sensory  organs  already  named,  is  familiar  to  all  as  the 
*  head  '  of  the  animal  ;  and  it  is  owing  to  the  fact  of  the 
clustering  of  sense-organs  on  this  part  that  the  head  con- 
tains internally  a  number  of  related  nerve  ganglia.  This 
aggregate  mass  of  ganglia  constitutes  the  *  Brain '  of 
invertebrate  animals.  It  forms  a  congeries  of  nerve 
centres,  differing  much  in  different  classes,  as  we  shall 
find,  not  only  in  regard  to  the  disposition  and  size,  but 
also  in  respect  to  the  relative  proportions  of  its  component 
parts.  The  size  of  the  respective  ganglia,  indeed,  neces- 
sarily varies  in  accordance  with  the  relative  importance 
and  complexity  of  the  several  sense  organs  already  men- 
tioned— those  of  Touch,  Taste,  Smell,  and  Sight. 

The  ganglia  thus  constituting  the  Brain  of  invertebrate 
animals  are  not  only  in  relation  each  with  its  own  par- 
ticuhxr  sensory  organs,  but,  in  addition,  we  find  the 
several  ganglia  brought  into  relation  among  themselves 
and  with  their  fellows  of  the  opposite  side  by  means  of 
connecting  or  commissural  fibres.  They  are,  moreover, 
often  connected,  by  means  of  much  longer  commissural 
threads,  with  other  nerve  ganglia  in  difi'crent  parts  of  the 
body. 

Hearing. — Another  special  sense  endowment  remains  to 
be  referred  to.  This  has  to  do  with  the  organism's  power 
of  appreciating  the  vibrations  causing 'auditory'  impressiona 
■ — a  power  which  is,  however,  probably  possessed  in  only  a 


Chap.  III.]  OF    SENSE    ORGANS.  65 

low  degree  by  most  invertebrate  animals.  Even  the  most 
perfect  form  of  the  organ  of  hearing  among  these 
animals  is  but  a  very  rudimentary  structure.  In  this 
respect  a  great  difference  exists  between  the  sense  of 
Sight  and  that  of  Hearing.  Whilst  the  eye  of  the 
Cuttle-fish  attains  a  degree  of  elaboration  not  falling  so 
very  far  short  of  the  most  perfect  form  which  the  organ 
displays  among  vertebrate  animals,  the  organ  of  hearing 
throughout  the  Invertebrata  is  remarkable  for  its  sim- 
plicity, and  remains  in  all  of  them  notably  inferior  to  the 
very  high  type  attained  by  this  sensorial  apparatus  in 
many  Mammals  and  in  Man. 

Like  the  sense  of  Sight  and  the  sense  of  Smell,  that  of 
Hearing,  even  in  its  simplest  grades,  serves  to  bring  the 
organism  into  relation  with  more  or  less  distant  bodies. 
It  is  only  necessary  that  these  latter  should  be  capable  of 
transmitting  sonorous  vibrations  through  water  or  air  to 
the  auditory  organs  which  become  attuned  to  receive  them. 

It  seems  just  possible,  however,  that  the  so-called 
*  auditory  saccules  '  of  the  Invertebrata,  may  have  more 
to  do  with  the  '  sense  of  Direction,'  or  of  the  organism's 
relations  with  space,  than  with  the  sense  of  Hearing.*  In 
Vertebrate  Animals,  it  would  appear,  that  both  these 
functions  are  associated  with  the  auditory  apparatus,  and 
it  is  by  no  means  certain  that  the  '  sense  of  Direction,'  or 
of  the  organism's  space-relations,  may  not  be  an  endow- 
ment more  primordial  than  that  of  Hearing. 

No  auditory  perception  seems  to  be  present  at  all — 
certainly  none  has  as  yet  been  detected  or  inferred  to  exist 
— in  many  of  the  lower  forms  of  life  ;  while  in  other 
animals,  though  possibly  existing,  its  organs  remain  as  yet 
unrecognized.  The  latter  condition  obtains,  for  instance, 
with  the  majority  of  Crustacea,  Spiders,  and  Insects. 
*  See  p.  218. 


66  THE    USE    AND    NATURE 

Judging  from  the  instances  in  which  *  auditory  sac- 
cules '  have  been  detected  in  Mollusks,  and  in  some  few 
representatives  of  the  classes  above  named,  it  seems  (and 
the  information  may  be  novel  to  many  readers)  that  the 
endowment  in  question  is  not  habitually,  or  even  usually, 
found  in  the  head,  or  in  direct  relation  with  one  of  the 
ganglia  composing  the  brain  of  Invertebrates.  In  some 
Heteropida,  and  their  allies,  however,  the  '  saccules,'  what- 
ever may  be  the  function  to  which  they  are  subservient, 
seem  to  be  in  immediate  relation  with  the  brain  ganglia.* 
Further  remarks  on  this  subject  must,  however,  be  de- 
ferred until  a  brief  description  has  been  given  in  future 
chapters,  of  the  nature  and  distribution  of  the  nervous 
system  in  some  of  the  principal  groups  of  the  Invertebrata. 

The  foregoing  are  the  commonly  received  modes  by  which 
organisms  are  impressed  from  without,  and  by  which  they 
attune  themselves  to  the  conditions  and  actions  occurring 
in  their  medium.  It  was  recognized  by  Democritus  and 
other  ancient  writers,  that  they  are  all  of  them  derivatives, 
or  more  specialized  modes  of  a  primordial  common  sensi- 
bility, such  as  is  possessed  by  the  entire  outer  surface  of 
the  organism.  Touch,  taste,  smell,  vision,  and  probably 
hearing,  are  sense  endowments,  having  their  origin  in 
organs  formed  by  a  gradual  differentiation  of  certain  por- 
tions of  the  external  or  surface  layer  of  the  body — that  is, 
of  the  part  in  which  common  sensibility  is  most  frequently 
called  into  play.  And  just  as  this  common  sensibility  is  a 
crude  or  general  sense  of  touch,  so  are  the  several  specinl 
senses  to  be  regarded  as  more  or  less  highly  refmed  modes 
of  the  same  sense  endowment. 

The  distribution  and  arrangement  of  nerves  in  the 
various  impressible  surfaces   have    certain  characteristics 

*  Siebold,  "Manuel  d'Anat.  Comp./'  p.  309,  Note  1. 


Ch.p.  TIL]  or    SENSE    ORGANS.  67 

which  have  heen  clearly  pointed  out  by  Herbert  Spencer. 
*'  At  the  surface  of  the  body,"  he  says,*  "  where  the  ex- 
tremities of  nerve  fibres  are  so  placed  as  to  be  most  easily 
disturbed,  we  generally  find  what  may  be  called  multipliers 
of  disturbances.  Sundry  appliances,  which  appearing  to 
have  nothing  in  common,  have  the  common  function  of 
concentrating,  on  the  ends  of  nerves,  the  actions  of  ex- 
ternal agents."  This  effect  is  produced  by  lenses  in  the 
eyes,  otoliths  and  other  bodies  in  the  organs  of  hearing, 
vibrissas  and  corpuscida  tactus  in  the  skin ;  all  of  which 
serve  to  exaggerate  the  effects  of  incident  forces  upon 
especially  sensitive  peripheral  expansions  of  the  nervous 
system.  "  The  ultimate  nerve  fibrillse,  ramifying  where 
they  are  most  exposed  to  disturbances,  consist  of  nerve 
protoplasm,  unprotected  by  medullary  sheaths,  and  not 
even  covered  by  membranous  sheaths.  In  fact  they 
appear  to  consist  of  matter  like  that  contained  in  nerve 
vesicles,  ....  and  may  be  regarded  as,  like  it,  more 
unstable  than  the  matter  composing  the  central  fibres  of 
the  fully  difterentiated  nerve  tubes.  .  .  .  This  peri- 
pheral expansion  of  the  nerve  on  which  visual  images  fall 
contains  numerous  small  portions  of  the  highly  unstable 
nerve  matter,  ready  to  change,  and  ready  to  give  out 
molecular  motion  in  changing.  It  is  thus,  too  [in  higher 
animals],  with  those  terminal  ramifications  of  the  auditory 
nerve  on  which  sonorous  vibrations  are  concentrated. 
And  there  is  an  analogous  peculiarity  in  the  immensely 
expanded  extremity  of  the  olfactory  nerve.  Here,  over  a 
large  tract  covered  by  mucous  membrane,  is  a  thick  plexus 
of  the  grey  unsheathed  fibres ;  and  among  them  are 
distributed  both  nerve  vesicles  and  granular  grey  sub- 
stance, such  as  that  out  of  which  the  vesicles  arise  in 
the  nervous  centres." 

*  "  Principles  of  Psychology,"  vol.  i  p.  35. 


68  THE    USE    AND    NATURE 

The  movements  of  locomotion,  or  of  limited  parts  of 
the  hody,  which  become  established  in  correspondence  with 
various  kinds  of  external  impressions,  tend  with  time  to  in- 
crease in  number,  definiteness,  and  complexity.  They  are, 
for  the  most  part,  to  be  classified  as  actions  subservient  to 
the  pursuit  and  capture  of  prey,  to  the  avoidance  of  enemies, 
to  the  union  of  the  sexes,  or  to  the  care  of  young. 

All  such  movements  are  found,  as  a  general  rule,  to 
have  the  effect  of  prolongirg  the  action  of  any  inflaences 
which  previous  individual  or  race  experiences  have  proved 
to  be  favourable  to  the  life  and  well-being  of  the  organism  ; 
and,  on  the  other  hand,  of  cutting  short  or  avoiding  influ- 
ences which  past  individual  or  race  experiences  have 
proved  to  be  contrary  to  its  general  well-being.  The 
capture  and  swallowing  of  food  are  ends  to  which  a  very 
large  proportion  indeed  of  the  definite  motions  of  most  of 
the  lower  organisms  are  directed ;  and  this  direction  of 
their  energies  is  only  a  special  case  to  be  included  under 
the  rule  above  indicated — ^just  as  efforts  to  escape  from 
predatory  neighbours,  are  other  opposite  instances  of  the 
same  rule. 

Visceral  Sensations  and  the  '  Muscular  Sense.' — 
In  addition  to  the  various  modes  of  impressibility  by 
external  influence  which  we  have  hitherto  been  considering, 
there  are  also  certain  other  modes  due  to  changes  in  the 
condition  of  internal  parts  of  the  organism.  These  are 
divisible  into  two  categories  :  (1)  impressions  emanating 
from  one  or  other  of  the  various  sets  of  viscera — such 
as  the  alimentary  canal  and  its  appendages,  the  respiratory 
organs,  the  genital  organs,  or  other  internal  parts  ;  and 
(2)  impressions  derivable  from,  or  in  some  way  attendant 
upon,  the  contractions  of  muscles. 

The  first  category  of  internal  impressions — those  eman- 


Chap.  III.]  OF    SENSE    ORGANS.  69 

ating  from  the  viscera — are  undoubtedly  very  important 
in  relation  to  animal  life  generally.  In  part,  they  have 
the  effect  of  causing  contractions  of  related  muscular  por- 
tions of  the  viscera — as  when  the  presence  and  pressure 
of  food  in  certain  portions  of  the  alimentary  canal  excites 
— it  may  be  through  local  ganglia — contractions  by  which 
the  food  is  propelled  farther  on.  In  part,  however,  they 
act  upon  the  principal  nerve  ganglia — those  constituting 
the  brain — in  such  a  way  as  to  excite  the  external  sense- 
organs  with  which  they  are  connected  to  a  higher  order  of 
activity.  Visceral  impressions  of  one  kind  may  cause  an 
animal  more  eagerly  to  pursue  prey,  whilst  those  of 
another  sort  may  tend  to  an  increased  alacrity  in  dis- 
covering a  mate.  In  these,  and  in  many  other  instances, 
internal  impressions,  reaching  the  cerebral  ganglia,  would 
seem  to  excite  a  higher  receptivity  for  certain  kinds  of 
external  impressions  and  a  corresponding  increased  readi- 
ness to  respond  on  the  part  cf  the  moving  organs  whose 
activity  is  related  to  such  conjoined  impressions  and 
promptings. 

With  the  second  set  of  impressions,  those  of  the  so- 
called  '  muscular  sense,'  we  have  at  present  nothing  to 
do.  They  differ  altogether  from  others,  whether  of  ex- 
ternal or  of  internal  origin,  by  the  fact  that  they  follow  or 
accompany  movements  whose  intensity  they  are  supposed 
to  measure,  and  do  not  of  themselves  incite  movements. 
Granting  that  such  impressions  have  a  real  existence, 
it  is  obvious  we  can  know  nothing  about  them  among 
Invertebrate  Animals,  since  they  have  only  a  subjective 
existence  and  do  not  of  themselves  alone  lead  to  move- 
ments. Our  only  knowledge  of  such  impressions,  as 
subjective  states,  must  be  derived  from  our  own  sensations 
together  with  what  other  fellow-men  are  able  to  describe. 


CHAPTER  IV. 

THE    NERVOUS    SYSTEM    OF   MOLLUSKS. 

For  (Several  reasons  it  will  be  advantageous  to  depart 
from  the  usual  zoological  order,  and  consider  first  the 
disposition  of  the  nervous  system  in  some  of  the  principal 
types  of  the  sub-kingdom  Mollusca. 

These  are  animals  mostly  aquatic  and  wholly  devoid  of 
hollow,  articulated,  locomotor  appendages.  Their  organs 
of  vegetative  life  attain  a  disproportionate  development, 
as  may  be  imagined  from  the  fact  that  some  of  the 
simplest  representatives  of  the  class  consist  of  mere 
motionless  sacs  or  bags,  containing  organs  of  digestion, 
respiration,  circulation,  and  generation.  The  most  complex 
Mullusks,  however,  are  active  predatory  creatures,  endowed 
with  remaikable  and  varied  powers  of  locomotion,  and  with 
sense  organs  which  are  both  keen  and  highly  developed. 
The  simpler  forms  are  represented  by  the  motionless 
Ascidian,  and  the  higher  by  the  active  and  highly  endowed 
Cuttle-fish. 

It  should  be  mentioned,  however,  that  the  tendency  of 
several  recent  investigations  has  been  to  separate  the 
class  to  which  the  Ascidians  belong  altogether  from  the 
Mollusca,  and  to  place  them  as  an  independent  group, 
having  affinities  to  the  lowest  Vertebrates. 

The  solitary  Ascidians   may  be  taken  as  the  typo  of 


Chap.  IV.]      THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 


71 


the  Tunicata.  Their  Hfe  of  relation  with  the  external 
world  is  of  the  simplest  description.  They  are  sta- 
tionary creatures,  having  even  no  prehensile  organs — 
their  food  being  brought  to  the  commencement  of  the 
alimentary  canal  by  ciliary  action. 

In  correspondence  with  such  a  simple  mode  of  life,  we 
might  expect  to  find  a  very  rudimentary 
nervous  system,  and  this  expectation  is  fully 
realized.  The  Tunicata  possess  a  single 
small  nervous  ganglion  lying  between  the 
bases  of  the  two  funnels  through  which 
water  is  taken  in  and  discharged  (fig.  21,  c). 
This  ganglion  receives  branches  from  the 
tentacula  guarding  the  orifice  of  the  oral 
funnel,  and  possibly  from  the  branchial 
chamber ;  whilst  it  gives  off  outgoing  fila- 
ments to  the  various  parts  of  the  muscular 
sac,    and   perhaps   to   the   alimentary  canal  rough    diagram- 

T  i?    ii  J.1  •     1  1  T        raatic    sketch    of 

and  some  ot  the  other  internal  organs.  In  j^g  Nervous  Sys- 
some  of  the  solitary  Tunicata  a  rudimentary  t^m.   (Soiiy  after 

,     p  ,.  .  ,  .  .        Cuvier.)    a,  Bran- 

visual  function  is  presumed  to  exist.  At  cwai  orifice ;  b, 
all  events,  pisjment-spots  are  situated  on,  or  excretory  onfice ; 

'   i-    CI  L  '  c,  nerve  ganghon 

in   very   close    relation    w^ith,    the    solitary  with  its  afferent 


and 
nerves. 


efferent 


ganglion. 

The  recent  investigations  of  Kupffer  tend 
to  show  that  this  extremely  simple  nervous  system,  never- 
theless, represents  a  decidedly  higher  type  of  organization 
than    had   been    previously    supposed.      Further    details 
cannot,  however,  here  be  given.* 

The  Brachiopods  are  among  the  oldest  and  most  wide- 
spread of  the  forms  of  life  in  the  fossil  state,  and  the 
geographical  distribution  of  their  living  representatives  at 

*  See  Gegenbauer's  "  Comp.  Anatomy,"  English  Translation, 
p.  395, 


72  THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 

the  present  clay  is  also  very  wide.-  Like  the  Tunicata,  they 
are  also  headless  organisms,  and  lead  a  sedentary  existence, 
attached  to  rock  or  stone  either  by  a  pedicle  or  by  one 
division  of  their  bivalve  shells.  The  mouth  is  unprovided 
with  any  appendages  for  grasping  food — nutritive  par- 
ticles being  again  brought  to  it  by  means  of  ciliary  currents. 
Numerous  muscles  exist  which  connect  the  valves  of  the 
shell  to  one  another,  and  with  the  enclosed  animal. 

Though  the  visceral  organization  of  the  Brachiopods 
is  somewhat  complex,  no  definite  Sense  Organs  have 
yet  been  detected  in  any  of  them.  The  nervous  system  of 
these  sedentary  animals,  moreover,  comprises  nothing  an- 
swering to  a  '  brain '  as  it  is  ordinarily  constituted — though 
ganglia  exist  aroimd  the  oesophagus  which  must  receive 
afferent  impressions  of  some  kind,  and  from  which 
branches  proceed  to  the  various  muscles  and  viscera  of 
the  body. 

Such  low  sensory  endowments  would  be  wholly 
incompatible  with  that  degree  of  visceral  complexity  of 
organization  which  the  Brachiopods  possess,  had  it  not 
been  for  the  fact  that  these  animals  lead  a  passive  exist- 
ence in  respect  to  quest  of  food.  The  absence  of  sense- 
organs  and  of  a  brain  is,  indeed,  only  compatible  with 
such  a  semi- vegetative  existence. 

The  Lamellibranchs,  or  ordinary  headless  bivalve 
Moilusks,  also  include  some  representatives — such  as  the 
Oyster  and  its  allies — which  lead  a  sedentary  life.  The 
valves  of  the  shell  in  Lamellilranchs  generally  are  lateral, 
instead  of  being  dorsal  and  ventral  as  amongst  the 
curious  Brachiopods  above  referred  to. 

The  mouth  of  the  Oyster  is  surrounded  by  four  labial 
processes  whose  functions  are  not  very  definitely  known. 
It  presents  no  other  ai)pendages  of  any  kind  in  the 
neighbourhood  of  the  mouth,  and,  as  in   the  two  types  of 


Chap.  IV.]      THE    NERVOUS    SYSTEM    OF    MOLLUSKS.  73 


Mollusca   already  described,  the  food  which  it  swallows  is 
brought  to   the   entrance  of  its  oesophagus  by  means  of 


ciliary  currents.     It  has  two   small  anterior 


or 


labial ' 


ganglia  (fig.  22,  a,  a,)  one  being  situated  on  each  side  of  the 
mouth.    They  are  connected  by  a  commissure  arching  over 
it,  and  also  by  a  more  slender  thread  beneath  the  mouth. 
From     this    lower    commissure, 
filaments  {e)  are  given   off  to  the 
stomach.     The  anterior   ganglia 
receive  nerves  (/)  from  the  labial 
processes  which   are  probably  for 
the  most  part  afferent  in  function 
— at  all  events,  these  processes 
have  no  distinct  muscular  struc- 
ture.    Two  long  parallel  commis- 
sures (d,  d)  connect  the  anterior 
ganglia  with  a  single  large  com- 
pound '  branchial '  ganglion  [h), 

situated    posteriorly,   and  close  to    Anterior    or     laMal    gangUa ;    b, 
-.  ,  _      posterior     or    branchial    ganglion 

the   great  adductor  muscle,     it 
gives  off  branches  to  this  muscle, 
to  each  half  of  the  mantle,  and  gangUa. 
to  the  gills  (c,  c). 

Other  more  active  Lamellibranchs  possess  a  muscular 
appendage  known  as  the  'foot',  which  is  in  relation  with  an 
additional  single  or  double  nervous  ganglion  (' pedal'),  and 
is  used  in  various  ways  as  an  organ  of  locomotion.  Speak- 
ing of  the  diverse  uses  of  the  foot  among  bivalves.  Prof. 
Owen  says  :*  "To  some  which  rise  to  the  surface  of  the 
water  it  acts,  by  its  expansion,  as  a  float;  to  others  it 
serves    by    its    bent    form    as    an    instrument    to    drag 


Fig.   22.  —Nervous  System  of  an 
Oyster.   (Todd  aftei  Garner.)  a,  a, 


(double) ;  /,  labial  nerves  c,  c, 
branchial  nerves ;  d,  d,  commis- 
sures Ijetween  labial  and  branchi.il 


them 


along   the 


sands  :    to    a    third    family    it    is 


Lect.  on  Comp.  Anat.  of  Invert.  Animals,"  p.  505. 


74 


THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 


harrowing   organ  ;    to   many  it   aids   in  the  execution   of 
short  leaps." 

The  hivalves  possessing  a  foot,  therefore,  present  three 
pairs  of  ganglia  instead  of  two — the  anterior  or  '  lahial', 


Fig.  23  —Nervous  Systoin  of  th ;  Conmiou  Mussel.  (After  Owen.)  I,  Tvabial  ganglia 
connected  by  a  short  conini  ssu  o  above  or  in  front  of  the  mouth;  b,  !>,  branchial 
ganglia  similarly  connected,  and  also  united  by  very  long  cords  (</,  d)  witli  the  labial 
ganglia ;  2K  bilobed  pedal  ganglion  sending  branches  to  tlie  muscular  foot  (,r),  and 
clo.'iely  connected  with  the  'auditory  saccules'  (s) ;  h,  h',  circum-pallial  plexus; 
y,  byssus.  by  which  the  animal  attaches  itself  to  external  substances. 


the  posterior  or  '  hranchial',  and  the  inferior  or  *  pedal'. 
It  occasionally  liai)peiis  that  the  ganglia  of  the  posterior 
or  even  of  the  inferior  pair  may  hecome  approximated  and 
fused  into  one. 


Chap.  IV.]    THE    NERVOUS    SYSTEM    OF    MOLLUSKS.  75 

The  fusion  of  the  posterior  ganglia  takes  place,  as  in  the 
Oyster  (fig.  22,  b),  when  the  branchise  from  which  they 
receive  nerves  {c,  c)  come  close  together  posteriorly.  On 
the  other  hand,  in  those  Mollusks  in  which  the  branchiaB 
are  farther  apart,  the  two  ganglia  remain  separate  and  are 
connected  by  a  short  commissure,  as  in  the  Common 
Mussel  (fig.  23,  h). 

The  separateness  or  fusion  of  the  inferior  or  '  pedal '  gan- 
glia depends  upon  the  size  and  shape  of  the  foot,  since 
the  nerves  in  relation  with  them  are  distributed  almost 
wholly  to  this  organ  and  its  retractor  muscles.  Where  the 
foot  is  broad  the  ganglia  remain  separate,  and  are  merely 
connected  by  a  commissure.  But  where  the  foot  is  small 
and  narrow,  as  in  the  Mussel,  the  two  ganglia  become 
fused  into  one  (fig.  23,  p). 

Some  of  the  special  senses  are  unquestionably  repre- 
sented amongst  these  headless  Mollusks,  though  the 
distribution  of  the  different  organs  is  very  peculiar. 
Thus  in  Pecten,  Pinna,  Spondylus,  Ostrsea,  and  many 
other  genera,  very  distinct  and  often  pedunculated  ocelli  are 
distributed  over  both  margins  of  the  'pallium'  or  mantle. 
These  vary  in  number  from  forty  to  two  hundred  or 
more,  and  are  in  connection  with  distinct  branches  of  the 
circumpallial  nerves.  In  the  Eazor-fish,  Cockle,  Venus, 
and  other  bivalves  possessing  prolongations  of  the  mantle 
known  as  '  siphon-tubes',  the  ocelli  are  situated  either  at 
the  base  or  on  the  tips  of  the  numerous  small  tentacles 
arranged  round  the  orifices  of  these  organs.  And  these 
parts,  in  such  bivalves  as  live  in  the  sand,  are  often  the 
only  portions  of  the  body  which  appear  above  the  surface. 
The  margins  of  the  mantle  are  also  garnished  by  a  number 
of  short  though,  apparently,  very  sensitive  tentacles,  in 
which  the  creature's  most  specialized  sense  of  touch  seems 
to  reside. 


76  THE    NERVOUS    SYSTEM    OF    MOLT.USKS, 

Some  of  these  tactile  appendages,  as  well  as  some  of 
the  ocelli,  send  their  nerves  to  the  branchial  ganglia, 
while  others,  situated  on  the  anterior  borders  of  the 
mantle,  send  filaments  to  the  labial  ganglia.  The  latter 
also  receive  filaments  from  the  so-called  labial  appen- 
dages, whose  function  is  uncertain,  though  it  has  been 
suggested  that  they  may  be  organs  of  taste  or  smell. 
Lastly,  in  close  relation  with  the  pedal  ganglia  or 
ganglion,  there  are  two  minute  saccules  (fig.  23,  s),  to 
which  an  auditory  function  is  usually  ascribed. 

Thus  we  find  amongst  these  headless  Mollusks  a  distri- 
bution of  specially  impressible  parts  or  sensory  organs, 
such  as  cannot  be  paralleled  among  any  other  animals. 
The  functions  which  we  shall  find  pertaining  to  the 
'  brain '  in  other  creatures  are  in  them  distributed  in  a 
very  remarkable  manner — so  that  such  organisms  may 
be  said  to  be  brainless  as  well  as  headless. 

The  Pteropods  constitute  another  interesting  class  of 
Mollusks,  which  lead  us  on  from  the  comparatively 
sluggish  Lamellibranchs  to  the  Gasteropods  and  the 
Cephalopods — organisms  which  possess  definite  and  wide- 
reaching  powers  of  locomotion,  as  well  as  a  distinct  head 
carrying  sense-organs  and  a  more  or  less  developed 
brain. 

The  possession,  by  many  members  of  this  class,  of  two 
fin-like  muscular  expansions  attached  to  the  side  of  the 
head  induced  Cuvier  to  give  them  the  above  class  name. 
According  to  Owen,  "  All  the  species  of  Pteropoda  are  of 
small  size ;  they  float  in  the  open  sea,  often  at  great 
distances  from  any  shore,  and  serve,  with  the  Acalepha3, 
to  people  the  remote  tracts  of  the  ocean.  In  the  latitudes 
suitable  to  their  well-being,  the  little  Pteropoda  swarm  in 
incredible  numbers,  so  as  to  discolour  the  surface  of  the 
sea  for  leagues ;  and  the   Clio  and   the  Limacina   con- 


Chap.  IV.]      THE    NERVOUS    SYSTEM    OF    MOLLUSKS.  77 

stitute,  in  the  northern  seas,  the  principal  article  of  food 
of  the  great  whales." 

Some  of  the  least  highly  organized  members  of  this 
class,  such  as  the  Hyalleidie,  possess  a  bivalve  shell,  and 
no  distinct  head  ;  but  in  other  Pteropods  devoid  of  a  shell, 
we  meet  with  a  higher  organization.  Thus  in  Clio  there 
is  a  distinct  head  bearing  sensory  appendages,  in  the  form 
of  two  tentacula  and  two  eyes,  and  containing  *  a  brain ' 
within.  The  brain  is  represented  by  two  connected  ganglia 
above  the  oesophagus,  which  are  in  relation,  by  means  of 
ingoing  nerves,  with  the  above  mentioned  sensory  organs. 
In  connection  with  another  commissure  uniting  these  two 
cerebral  ganglia  and  which  passes  under  the  first  part  of  the 
alimentary  canal,  are  two  'pedal'  and  two  'branchial'  ganglia 
pretty  close  together.  These  two  pairs  of  ganglia  exist 
separately  in  Clio  and  its  allies,  though  they  are  combined 
into  one  quadrate  mass  in  Hyalea.  In  Clio  two  '  auditory 
saccules '  are  in  connection  with  the  anterior  sub-oesopha- 
geal  ganglia — that  is,  with  the  pair  which  corresponds 
with  the  'pedal'  ganglia  of  the  common  bivalve  Mollusks. 

Gasteropods  constitute  a  class  of  organisms  which,  in 
point  of  numbers,  can  only  be  compared  with  the  still 
more  numerously  represented  class  of  Insects.  Their 
name  is  derived  from  the  fact  that  they  crawl  by  means  of 
a  large  muscular  expansion  or  '  foot'  stretched  out  beneath 
the  viscera.  The  locomotion  of  members  of  this  class 
may  be  said  to  be,  in  the  main,  dependent  upon  their  own 
individual  efforts,  so  that,  in  this  respect,  they  differ 
widely  from  Pteropods,  whose  movements  from  place  to 
place  are  brought  about  chiefly  by  winds  driving  them 
along  the  surface  of  the  water  on  which  they  float. 

Some  Gasteropods  are  terrestrial,  air-breathing  animals, 
though  by  far  the  greater  number  are  aquatic  and  breathe 


78  THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 

by  means  of  gills.  Bat  being  all  of  tbem,  as  Prof.  Owen 
says,  "  endowed  with  power  to  attain,  subdue,  and  devour 
organic  matter,  dead  and  living,"  we  find  their  Nervous 
System  not  only  better  developed,  more  complex  and  con- 
centrated, but  also  in  relation  with  more  highly  evolved 
organs  of  special  sense  and  exploration.  This  system 
offers  considerable  variations  in  general  arrangement,  and 
as  regards  the  relative  positions  of  its  ganglia,  though 
these  modifications  are,  to  a  great  extent,  referable  to 
differences  in  the  outward  configuration  of  the  body. 

The  wide  differences  in  external  form  which  are  to  be 
met  with  among  Gasteropods  may  be  well  illustrated  by 
comparing  the  Limpet  or  the  Chiton  with  the  Snail. 
Here  differences  in  habit  are  also  marked,  so  that  we 
almost  necessarily  meet  with  very  notable  variations  in  the 
disposition  of  the  principal  parts  of  the  nervous  system. 

In   the  Limpet  two   small  cerebral   ganglia   (fig.  24  a) 
exist,  which   are  widely  separated  from  one  another,  and 
lie  at  the  side  of  the  oesophagus.     Each 
receives  a  rather  large  nerve  from  one  of 
the  tentacles,  and  a  smaller  optic  nerve. 
A  commissure  above  the  oesophagus  con- 
nects these    cerebral    ganglia  with  one 
^^n'f^f^i\.       another,  while  each  of  them  is    also  in 
^U^        \\\       relation    by  means  of    two   descending 
Fiu.  -21.  —  Nervous   commissurcs  with  a  series  of  four  con- 
system    of    Common       ^   -^  ganglia  forming    a   transversely 

Limpet.      (Todd     after  fc-        o  o  J 

Garner.)  a,  Cerebral  arranged  row  beucath  the  oesophagus. 
!n7t  peda/gan^r!  Of  thcse  thc  two  median  ganglia  (h) 
D,   pharyngeal  and  K  corrcspoud  witli  the  pcdal,  wliilc  the  two 

labial  ganglia.  (/  and  ''>..,.  t         .,■^       ,-,         ■, 

Commissures ;  p,  tcnta-  cxtcmal  (c)  corrcspoud  With  tiic  orau- 
cuiar  nerve;  i,  optic   ^^j^'g^j    ganglia,    though    they    are    here 

separated  from  one    another  by  an  un- 
usually wide  interval. 


Ohap.  IV.]     THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 


79 


4-cJ 


However  small  and  nndeveloped  the  duplex  brain  of 
the  Limpet  may  be,  this  organ  exists  in  an  even  more 
rudimentar}'  state  in  its  close  ally^  the  Chiton,  which  is 
about  the  most  simply  organized  of  all  the  Gasteropods, 
It  has  neither  tentacles  nor  eyes,  and, 
as  a  consequence,  no  distinct  supra- 
cesophageal  ganglia  are  found  (fig.  25). 
There  is,  in  fact,  nothing  to  which  the 
term  '  brain  '  can  be  appropriately  ap- 
plied. 

If  we  turn,  however,  to  the  very 
active  Snail,  we  find  the  nervous  sys- 
tem existing  in  a  much  more  deve- 
loped and  concentrated  form.  There 
is  a  large  ganglionic  mass  (fig.  26,  I) 
situated  over  the  oesophagus,  each 
half  of  which  receives  a  considerable 
bundle  of   nerve-fibres   (/)   from  the      fig.  25.  — Nervous  sys- 

,7 ,        p     ,  . -,  1   •    1     •         'J  teni  of  Chiton  marmoratus. 

eye   (6)   of  the  same  side,  which  is  situ-     (Gamer.)      v>,    Pharyngea 

ated  at  the  tip  of  the  larger  tentacle,   ganglion  (left);  b,  pedai 

.  ^1  1  ni  i?    ganglion  (right)  ;  c,   bran- 

It    also    receives    another    bundle   01  cMai  ganglion;  i,  upper 
nerves  (Ji)  from  the  small  tentacle  on  portion  of  oesophageal  ring 

V    ^  _   ^  devoid     of     any     distinct 

each  side,  which  has  in  all  probability  cerebral  ganglia. 
a  tactile  function.  The  '  auditory  sac- 
cules '  are  here  in  their  exceptional  position — that  is  in 
immediate  relation  with  the  posterior  aspect  of  the  ganglia 
constituting  the  brain,  though  in  most  other  Gasteropods 
they  are,  as  in  bivalve  Mollusks,  found  in  connection  with 
the  pedal  ganglia.  There  is  one  group,  however — the 
Heteropoda — in  which  the  '  auditory  saccules '  seem  to  be 
always  in  direct  relation  with  the  cerebral  ganglia,  as  in 
Carinaria  and  Pterotrachea.* 


*  See  Fig. 
TransL) 


187,  p.  354,  Gegeabauer's  "  Comp.  Anat."   (Engl. 


80 


THE    NERVOUS    SYSTEM    OF    MOELUSKS. 


Naturalists  now  generally  admit  that  Snails  and  their 
allies  are  endowed  with  a  rudimentary  sense  of  smell, 
though  hitherto  they  have  heen  unahle  to  locate  the  endow- 
ment in  any  particular  organ  or  surface-region. 

The  brain  of  the  Snail  is  connected,  by  means  of  a  thick 

cord  or  commissure  on 
each  side  of  the  oeso- 
phagus, with  a  long  and 
curved  double  ganglionic 
mass  (/»).  This  latter 
body,  situated  beneath  the 
oesophagus,  represents  the 
pair  of  pedal  and  the  pair 
of  branchial  ganglia  of  the 
bivalve  Mollusks.  Here 
nerves  are  received  from 
the  integument  and  given 
off  to  the  muscles  of  the 
foot ;  while  they  are  also 
received  and  given  off  from 
the  respiratoi'y  and  other 


FiG.  20. —Head  .and  Nervous  System  of 
the  Common  Garden  Snail.  (Owen.)  /.Cere- 
bral ganglia  receiving  nerves  from  smaller 
( a)  and  fi'om  larger  tentacles  bearing  ocelli 
(b) ;  m,  sub-oesopbageal  ganglionic  ma^a, 
representing  a  pair  of  pedal  and  a  i)air  of 
brancbial  ganglia.  Two  of  the  tentacles  are 
represented  in  different  states  of  retraction. 


The  nervous  system  of 
one  of  the  Nudibranch 
Mollusks  has  been  repre- 
sented in  fig.  17.  It  is  also 
highly  developed  and  concentrated,  whilst  its  sensory  and 
motor  ganglia  are  unusually  distinct  and  separate  from  one 
another.  A  somewhat  analogous  arrangement  of  the  jirin- 
cipal  nerve  centres  exists  in  the  Common  Slug  (fig.  27),  only 
here  the  motor  ganglia  of  the  two  sides  are  fused  together, 
as  in  the  Snail,  instead  of  being  widely  separated  as  in 
Eolis  and  its  allies.  They  consequently  occui)y  an  inferior 
rather  than  a  superior  and  lateral  position  in  regard  to 


Chap.  IV.]     THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 


81 


the  oesopbagus.  The  bmncliial  ganglia  arc,  moreover, 
fused  with  them,  instead  of  with  the  cerebral  as  they  are 
in  Eolis. 

The  nervous  system  in  the  Cephalopods  presents 
many  peculiarities,  -which  can,  however,  be  only  very 
briefly  referred  to  here.  Owing  to 
an  extreme  amount  of  shortening 
of  their  commissures,  the  principal 
ganglia  are  closely  aggregated  in  the 
head.  The  nervous  system  is,  in- 
deed, .more  concentrated  and  com- 
plex than  in  other  Mollusks,  and  the 
animals  themselves  are  notable  for 
the  high  degree  of  development  of 
some  of  their  sensory  organs  as 
w^ell  as  for  their  great  powers  of 
locomotion. 

The  body  of  the  Pearly  Nautilus, 
contained  within  the  last  chamber  of 
its  coiled  and  loculated  shell,  is  en- 
veloped by  a  muscular  mantle  open 
anteriorly,  round  the  head  and  its 
numerous  sensory  appendages.  Ac- 
cording to  Owen,* 
tentacles  with  which  the  Pearly 
Nautilus  is  provided  amounts  to  no 
less  than  ninety,  of  which  thirty- 
eight  may  be  termed  digital,  four  ophthalmic,  and  forty- 
ei^'ht  labial."  The  eyes,  not  so  well  developed  as  in 
the  Cuttle-fish,  are  also  in  relation  with  smaller  optic 
ganglia  (fig.  28,  o  o).  Near  them  are  two  hollow  bodies, 
regarded  by  Valenciennes  as  olfactory  organs,  the  nerves 
from  which  join  the  same   ganglia.     The  situation   and 

*  "  Lectures  on  Comp.  Anat.  and  Physiol,  of  Invert.,"  p.  581. 


Fig.  27. — ^.'eivons System  of 
the  number  of  the  common  Slug  (Solly  after 
Baly. )  A  A,  Cerebral  ganglia  ; 
B  B,  branchial  ganglia  and  c, 
pedal  ganglia  fused  into  one 
mass  ;  d,  phaiyngeal  gauglia. 


1L%A 


82 


THE  NERVOUS  SYSTEM  OF  MOLLUSKS. 


relations  of  auditory  organs  in  this  animal  have  not  been 

definitely  settled. 

In  regard  to  organs  of  taste  and 
touch,  Owen  writes  as  follows, — 
*'  The  complex  and  well  developed 
tongue  of  the  Pearly  Nautilus  ex- 
hibits in  the  papillae  of  its  anterior 
lobes  and  in  the  soft  ridges  of  its 
root  the  requisite  structure  for  the 
exercise  of  some  degree  of  taste  : 
.  .  .  the  sense  of  touch  must  be 
specially  exercised  by  the  numer- 
ous cephalic  tentacles,  which,  from 
their  softness  of  texture,  and 
especially  their  laminated  inner 
surface,  are  to  be  regarded  as 
organs  of  exploration  not  less  than 
as  organs  of  prehension."  The 
nerves  of  tbese  tentacles,  must  be 
both  sensory  and  motor  ;  they  are 
in  connection  with  a  large  double 
ganglionic  mass  (h  h)  situated 
beneath  the  oesophagus  but  in 
front  of  the  other  sub-oesophageal 
ganglion  (c  c),  which  is  thought 
by  Owen  to  represent  "the  liomo- 
logues  of  both  the  branchial  and 
pedal  ganglions  in  the  inferior 
Moll u sea."  The  latter  pairs  of 
ganglia  are  clearly  combined  in 
function,  since  the  locomotions  of 
the  Nautilus,  like  the  much  more 
rapid  locomotions  of  other  Cepha- 
ncipally  eftected  "  in  a  succession 


Fio.  28. — Nervous  System  of 
Pearly  Nautilus.  (Gegenbauer 
after  Owen.)  a  a,  Cerebral  gan- 
glia, constituting  the  brain  ;  o  o, 
optic  ganglia  in  communication 
with  cerebral  ganglia,  which  are 
also  connected  with  a  lower  gang- 
lionic mass(/j  b),  receiving  nerves 
((  (')  from  the  tentacles  and  other 
pirts  about  the  muutli,  partly 
sensory  and  partly  motor.  The 
cerebral  ganglia  are  in  addition 
united  to  a  posterior  sub-ceso- 
phageal  mass  (c  c),  supposed  to 
represent  a  pair  of  pedal  and  a 
pair  of  branchial  gan^jlia.  m  m. 
Motor  nervts;  d  d,  branchial 
nerves  and  ganglia. 


lopods,  seem  to  be  pri 


Chap.  IV.]    THE    NERVOUS    SYSTEM    OF    MOLLUSKS. 


83 


of  jerks,    occasioned  by  the  reaction   of   the  respiratory 
currents  upon   the  surrounding  water  " — these   currents 


Fig.  29.— Nervous  System  of  the  Common  Cuttle-Fish  {Sepia  officinalis).  (Owen.) 
1,  DoTible  supra-oes -phageal  ganglion  developed  from  upper  commissure;  %> p,  cut 
surfaces  of  the  cartilaginous  cranium  ;  2  2,  optic  ganglin  ;  4  4,  posterior  sub-oeso- 
ph  igeal  ganglia  (anterior  sub-cesophageal  ganglia  in  connection  with  nerves  of  feet 
and  tentacles,  6  6,  not  seen  in  this  view)  ;  7  and  8,  ganglia  in  connection  with  the 
pharynx  and  mouth,  connected  by  nerves  (5  5)  with  the  cerebral  lobes  ;  13  13,  great 
motor  nerves,  of  the  mantle  and  other  parts,  with  {(I  their  gnnglia ;  14,  e  c,  respiratory- 
nerves  ;  k  k,  small  tubercles  in  connection  with  optic  ganglia. 

being  produced  by  the  expulsive  contractions  of  a  powerful 
muscular  funnel  continuous  with  a  portion  of  the  mantle. 
In  the  Cuttle-fish  one  of  the  most  striking  character- 


84     THE  NERVOUS  SYSTEM  OF  MOLLUSKS. 

istics  of  the  principal  nerve-centres  is  the  fact  of  the  exist- 
ence of  a  very  large  optic  ganglion  (fig.  29,  2)  on  each 
side,  in  connection  with  an  extremely  well-developed  eye. 
Each  optic  lobe,  according  to  Lockhart  Clarke,  is  "as 
large  as  the  rest  of  the  cephalic  ganglia  on  both  sides 
taken  together."  From  each  of  these  lobes  an  optic 
peduncle  passes  inward  to  join  a  supra- cesophageal  gan- 
glionic mass,  wdiich  bears  on  its  surface  a  large  bilobed 
ganglion  (1),  thought  by  Clarke  to  be  homologous  w^ith 
the  cerebral  lobes  of  fishes.  It  is  connected,  by  means 
of  two  short  cords,  with  a  much  smaller  bilobed  ganglion, 
known  as  the  pharyngeal  (7).  This  latter  ganglion  re- 
ceives nerves  from  what  are  presumed  to  be  the  organs  of 
taste  and  smell,  and  gives  off  nerves  to  the  tongue  and 
powerful  parrot-like  jaws  with  which  the  creature  is  pro- 
vided. 

The  supra-oesophageal  mass  is  connected  by  cords,  at 
the  sides  of  the  ossopbagus,  with  a  very  large  ganglion 
lying  beneath  it  (4),  which  is  i:)artially  divided  into  an 
anterior  and  a  posterior  division.  The  anterior  division — ■ 
regarded  by  Huxley  as  in  part  homologous  with  the  pedal 
gangha  of  lower  Mollusks — is  in  relation  by  means  of 
large  nerves  (e)  with  the  feet  and  tentacles.  A  com- 
missure also  unites  it  with  the  pharyngeal  ganglion,  so 
that  the  tentacles  and  arms  are  thus  able  to  be  brought 
into  correlated  action  with  the  jaws.  The  posterior 
portion  of  the  sub-oesophageal  mass  receives  nerves  from, 
and  also  gives  off  nerves  (14)  to,  the  branchia)  and  other 
viscera,  as  well  as  to  the  muscular  mantle  (is,  13). 

The  '  auditory  saccules '  and  their  nerves  are  connected 
with  this  great  branchio-pallial  ganglion.  These  organs 
are  lodged  in  the  substance  of  the  cartilaginous  framework 
{p  p)  investing  the  nerve-ganglia — a  structure  which  seems 
to  answer  to  a  rudimentary  skull  or  cranium. 


Chap.  IV.]    THE    NERVOUS    SYSTEM    OF    MOLLUSKS.  85 

The  locomotions  of  Cattle-fislies  are  largely  brought 
about  by  contractions  of  the  pallial  chamber,  though  these 
same  contractions  of  the  pallium  are  also  subservient,  as 
in  the  Nautilus,  to  the  respiratory  function. 

The  large  share,  therefore,  which  the  branchio-pallial 
ganglia  take  in  bringing  about  and  regulating  the  move- 
ments of  these  animals,  would  seem  in  part  to  explain  the 
connection  of  the  *  auditory  saccules '  with  them,  since  in 
the  great  majority  of  other  Mollusks  in  which  these 
organs  are  known  to  occur,  they  are  found  to  be  in  primary 
relation  with  the  principal  motor  centres.  Whatever  may 
be  the  full  explanation  of  these  remarkable  relations,  the 
fact  remains  that,  even  in  the  Cuttle-fish  tribe,  the  super- 
ficial connections  of  the  so-called  '  auditory  saccules/  are 
still  away  from  the  brain. 


CHAPTER  V. 

THE   NERVOUS    SYSTEM    OF    VERMES. 

Nothing  distinctly  answering  to  a  Brain  is  to  be  found  in 
some  other  of  the  lowest  animals  in  which  a  nervous 
system  exists.  It  is  thus,  for  instance,  with  Star-fishe3 
and  the  larger  Nematoid  Entozoa.  What  most  nearly 
resembles  such  an  organ  in  Star-fishes,  consists  of  a  mere 
band  of  nerve  fibres,,  surrounding  the  commencement  of 
the  oesophagus,  and  containing  a  few  nerve-cells  partly 
between  its  fibres  and  partly  in  groups  slightly  removed 
therefrom.  The  absence  of  any  distinct  ganglia  in  the 
neighbourhood  of  the  mouth  is  doubtless  due,  in  the  main, 
to  the  form  of  these  animals,  and  their  low  type  of  organi- 
zation. Each  arm  or  ray  contains  its  own  nervous 
system,  so  that  the  ring  or  band  round  the  mouth  seems 
to  be  little  more  than  a  commissure  connecting  such 
otherwise  distinct  parts  of  the  common  system.  These 
Echinodcrms  are,  however,  here  only  incidentally  re- 
ferred to. 

In  the  larger  parasitic  Nematoids  the  nervous  system  is 
more  concentrated.  The  oesophageal  ring  and  imme- 
diately adjacent  parts  constitute  almost  all  that  is  as  yet 
known  of  their  nervous  system,  but  it  contains,  or  is  in 
relation  with,  a  larger  number  of  ganglion-cells  than 
the  similar  part  in  Star- fishes.  Thus,  in  addition  to  the 
cells  intermixed  with  the  fibres  of  the  ring  itself,  there  are 
five  or  six  groups  adjacent  to  and  in  connection  with  it, 


Chap.  V.]       THE    NERVOUS    SYSTEM    OF    VERMES.  87 

wliicli  receive  fibres  from  certain  large  papillae  surrounding 
the  mouth.  These  papilliB  would  seem  to  be  the  principal 
sensory  organs  of  the  Nematoid.  By  means  of  the  connect- 
ing nerve-fibres  and  ganglion-cells  they  are  brought  into 
relation  with  the  nervous  ring,  and  from  this  latter  out- 
going fibres  are,  doubtless,  given  off  to  the  four  great 
longitudinal  muscular  bands  by  which  the  movements  of 
the  organism  are  effected.  The  distribution  of  such  motor 
nerve-fibres,  however,  has  not  been  distinctly  traced. 

The  absence  of  ganglionic  swellings  on,  or  in  connec- 
tion with,  the  oesophageal  ring  of  Nematoids  is  probably 
dependent  upon  the  comparative  simplicity  and  limited 
number  of  the  impressions  capable  of  being  received 
through  their  cephalic  papillae. 

Among  other  representatives  of  the  sub  -  kingdom 
Vermes,  the  nervous  system  varies  a  good  deal  in  minor 
details,  in  accordance  with  the  degree  of  organization,  and 
with  the  diversity  of  the  sensory  and  locomotor  endow- 
ments of  the  several  organisms.  The  broad  features  of 
the  nervous  system,  however,  are  comparatively  similar 
in  all — especially  in  the  most  typical  representatives  of 
this  sub-kingdom,  which  contains  so  many  aberrant  types. 
Only  a  very  few  forms  will  be  here  referred  to. 

The  Nemerteans,  a  class  of  marine  worms,  possess 
a  very  simple  nervous  system.  They  have  soft,  un- 
segmented,  and  highly  contractile  bodies,  covered  with 
cilia,  but  are  otherwise  wholly  devoid  of  all  external 
appendages.  On  the  anterior  extremity  of  the  body,  a  little 
posterior  to  the  mouth,  two,  four,  or  more  specks  of  pig- 
ment are  met  with  (fig.  30,  e,  e),  which  are  conjectured  to 
serve  the  purpose  of  rudimentary  ocelli ;  and  whilst  the 
animal  is  moving  from  place  to  place  this  anterior  part  of 
its  body  doubtless  acts  also  as  its  principal  tactile  surface. 
Nerve-fibres  proceed  from  these  regions,  and  converge  so 


88 


THE    NERVOUS    SYSTEM    OF    VERMES. 


as  to  form  three  or  four  nerve-trunks  on  each  side,  which 
enter  a  comparatively  large  compound  ganglionic  mass 
{a,  a)  lying  on  the  lateral  aspects  of  the  sheath  of  the 
proboscis.    Each  of  these  masses  is  pyriform  in  shape,  and 

composed  of  a  sensory  and 
a  motor  ganglion  fused  into 
one.  It  is  connected  with 
its  fellow  by  means  of  two 
commissures,  one  of  which 
passes  over,  and  the  other 
beneath,  the  proboscis. 

It  is  difficult  to  trace  the 
ultimate  distribution  of  the 
nerve-fibres  in  these  crea- 
tures ;  so  that,  although 
fibres  can  be  followed  nearly 
up  to  the  pigment-spots, 
none  have  been  detected  in 
immediate  continuity  there- 
with. The  inferior  com- 
missure (c)  between  the  two 


Fig.  30.— Head  and  Brain  of  a  Nemertean. 
{Tetrastemma  melanocep/iala.)    a,  o.    Com- 
pound lateral   ganglia  ;    h,  narrow    upper     ganglionic  maSSCS  is  sllOrtcr 
commissure  between  which  and  the  much 
thicker  inferior  commi-ssure,  c,  the  cesopha- 


and  much  thicker  than  the 

gus  passes  ;  d,   d,  the  great  lateral  nerve     upper.      The  tWO  great  latC- 
cords  ;  e,  e,  pigment  spots,  or  rudimentary  177 

ocelli.   (After  Mcintosh.)  ral  nervc-trunks  {a,  a)  start 

from  the  ganglia,  and,  pro- 
ceeding along  the  sides  of  the  body,  give  off  numerous 
branches  to  the  longitudinal  and  circular  muscles  between 
which  they  are  situn,ted. 

Tactile  and  possibly  gustatory  impressions,  together 
with  impressions  produced  by  light  or  darkness,  doubtless 
come  from  the  anterior  extremity  of  the  organism  to  the 
anterior  part  of  the  pyriform  ganglia  on  either  side  ;  and 
are  thence  reflected  from  the  posterior  parts  of  these  bodies 


Chap,  v.]       THK    NERVOUS    SYSTEM    OF    VERMES. 


89 


along  related  channels  in  the  great  efferent  handles,  the 
fibres  of  which  proceed  to  the  contractile  proboscis  and 
also  to  the  muscles  on  one  or  both  sides  of  the  body. 
Other  departments  of  the  nervous  system  may  exist  in 
these  animals,  though  as  yet  none  have  been  detected. 

In  the  coAmon  Medicinal  Leech  the  nervous  system  is 
somewhat  differently  developed.     The  lateral  ganglia  of 
the  NemertidaB   are  replaced  by  two  small 
upper  ganglia    (fig.   31,    a),    connected  by 
lateral    commissures    with  a  single   lower 
ganglion  (c)  ;  and,  as  a  consequence  of  this 
coalescence  of  the  two  sub-oesophageal  gan- 
glia,  we   have, , instead  of  the  two  lateral 
cords  of  the  Nemertidse,  a  double  ventral      ^^j^^^^^ 
nervous   cord  traversing  the  whole  length 
of  the  body.     The  two  cords  approximate  so 
closely  as  to  be  almost  fused  into  one,  and 
they  bear  a  series  of  ganglia — one  for  every 
three  or  four  of  the  segments  into  which  the 
body  of  the  animal  is  obscurely  divided. 

The  bilobed  ganglion  above  the  oesopha- 
gus, which  is  mainly  sensory,  receives  fibres 
from  the  tactile  lips,  together  with  ten  dis- 
tinct filaments  from  as  many  pigment- spots 

or  ocelli  {h  h),  situated  round  the  margin  of       ^       ^^ 

the  upper  lip.  From  this  bilobed  ganglion,  \-^y|4^ 
corresponding  with  the  brain  proper  of 
higher  animals,  a  cord  descends  on  each 
side  of  the  oesophagus,  and  the  two  join  the 
heart-shaped  sub-oesophageal  ganglion  (c), 
from  which  efferent  nerves  are  given  off  to 

Fig.  31. — Nervous  Sy.stem  of  the  Medicinal  Leech.  (Owen.)  a,  Dotible  supTO- 
oesoiahage&l  ganglion  connected  by  nerves  with  b,  6,  rudimentary  ocelli ;  c,  the  double 
infra-cesopt  ageal  ganglionic  ma^a,  which  is  continuou3  with  the  double  ventral 
cord,  bearing  distinct  compound  ganglia  at  intervals. 


^ 


>^ 


:M 


90  THE    NERVOUS    SYSTEM    OF    VERMES. 

the  muscles  whose  business  it  is  to  move  its  three  saw- 
like jaws,  as  well  as  to  the  muscles  of  the  oral  sucker. 
This  lower  ganglion  is  in  part  analogous  to  the  '  me- 
dulla oblongata  '  of  vertebrate  animals.  It  is  continuous 
with  the  double  ventral  cord,  on  which  twenty  equidistant 
rhomboidal  ganglia  are  developed.  Each  of  these  ganglia 
gives  off  two  nerves  on  either  side,  whose  branches  are 
distributed  to  the  parietes  and  the  muscles  of  adjacent 
segments. 

In  this  animal  a  simple  filament  is  also  given  off  from 
the  posterior  part  of  the  supra-cesophageal  ganglion,  which 
is  distributed  along  the  dorsal  aspect  of  the  alimentary 
canal.  It  foreshadows  an  important  system  of  fibres  in 
higher  animals,  corresponding  partly  with  the  pneumo- 
gastric  nerves,  and  partly  with  the  '  sympathetic  system.' 
As  it  exists  amongst  the  Invertebrates  it  is  known  as  the 
*  stomato-gastric  system  '  of  nerves.  In  other  members 
of  the  invertebrate  series  it  frequently  takes  origin  from 
the  commissures  connecting  the  upper  and  lower  oeso- 
phageal ganglia,  rather  than  from  the  upper  ganglia  them- 
selves. In  some  of  the  woi-ms,  in  which  such  an  ar- 
rangement exists,  the  stomato-gastric  system  is  also  more 
complicated. 

In  the  Earthworm  the  body  is  composed  of  a  multitude 
of  ring-like  segments,  provided  with  lateral  setoB  which 
the  animal  calls  into  play  during  its  subterranean  loco- 
motions. It  possesses  no  distinct  ocelli,  and,  having 
regard  to  its  mode  of  life,  this  is  not  surprising. 

The  supra-OBSophageal  ganglia,  which  together  represent 
the  brain  of  the  Earthworm,  receive  a  nerve  trunk  on  each 
side,  composed  of  fibres  coming  from  the  tactile  upper  lip; 
and,  as  no  sensory  filaments  of  a  different  order  are  known 
to  be  immediately  connected  therewith,  the  functions  of 
the  brain  in  this  animal  must  be  comparatively  simple. 


Chap.  V.]       THE    NERVOUS    SYSTEM    OF    VERMES. 


91 


The  lip  is  regarded  as  an  organ  of  touch,  hut  it  is 
equally  prohable  that  it  is  capable  of  receiving  more 
special  impressions  representing  rudimentary  tastes.  The 
separation  between  these  modes  of  sensibility  in  such  low 
organisms  is  probably  somewhat  indefinite. 

The  double  ventral  cord  has  a  fibrous  structure  along 
its  upper  surface,  whilst  below  there  is 
an  irregular  stratum  of  ganglion  cells. 
These  cells  are  more  abundant  about 
the  centre  of  each  body-segment,  so 
that  their  aggregation  gives  rise  to  a 
series  of  rudimentary  ganglia  in  these 
situations.  From  every  one  of  the 
ganglionic  swellings  two  nerves  are 
given  off  on  each  side ;  v\^hilst  a  third 
pair  issues  from  the  cord  itself,  just 
anterior  to  the  swelling,  and  is  dis- 
tributed along  the  anterior  boundaries 
of  the  segment.  In  Serpula,  one  of  the 
small  tube-dwelling  marine  worms,  the 
ventral  ganglia  are  also  very  minute, 
and  those  of  the  two  sides,  together 
with  the  ventral  cords,  lie  some  distance 
apart,  and  are  connected  by  a  series  of 

.  ^  T   .  Fig.   S2.- Nervous    Sys- 

COmmiSSUreS  (fig.  32,    b).        in  this  dlS-     tem   of    Serimla   cntortu- 

position  of  the  great  nervous  cords  we  gSSXlfrX^l?'- 

have   something  intermediate  between  phageai  gangUa;  6,  sub- 

their  lateral  position  in  the  Nemerteans,  ^/gangiSliated^ cords  ^n, 

and  their  contis^uous  mid-ventral  posi-  motor  buccal  nerves ;  <,tac- 

^  tile  nei'ves. 

tion  in  the  Leech  and  the  Earthworm. 

As  in  the  latter,  so  m  Serpula,  the  afferent  nerves  entering 

the  brain  {t)  seem  to  be  in  the  main  tactile. 

The  oesophageal  ganglia  in  the  Earthworm  are,  propor- 
tionately to  the  rest  of  the  nervous  system,  much  smaller 


92  THE    NERVOUS    SYSTEM    OF    VERMES. 

than  in  the  Nemerteans  ;  and  this  is  perhaps  due  in  great 
part  to  the  existence  in  it  of  the  numerous  segmental 
ganglia, — structures  which  are  absent  in  the  above-men- 
tioned marine  worms.  The  movements  of  the  Nemer- 
teans, Hke  those  of  the  Nematoids,  are  probably  much 
more  exclusively  under  the  control  of  the  oesophageal 
ganglia  than  are  those  of  the  segmented  Earthworm — in 
which  each  of  the  body  ganglia,  doubtless,  has  much  to  do 
with  bringing  about  the  contraction  of  its  contiguous 
muscles  in  the  same  segment. 

The  Earthworm  has  a  more  complex  visceral  structure 
than  is  to  be  met  with  among  the  Nemerteans ;  and  it 
presents  distinct  evidences  of  a  nervous  interconnection 
between  its  internal  organs  and  some  of  the  principal 
nerve-centres.  Lockhart  Clarke  has  described  a  complicated 
gauglionic  network  on  each  side  of  the  oesophagus,  start- 
ing from  the  lateral  commissures  and  sending  prolonga- 
tions to  the  intestine  and  other  parts.  By  means  of  this 
principal  visceral  system  of  nerves,  the  internal  organs  are 
brought  into  relation  with  one  another,  and  with  the 
nervous  system  of  animal  life — that  is,  with  those  parts 
of  it  having  to  do  more  especially  with  the  relation  of  the 
organism  to  its  medium. 


OHAPTEE  VI. 

THE    NERVOUS    SYSTEM   OF   ARTHROPODS. 

The  next  sub-kingdom,  Arthropoda,  comprises  tlie 
Myriapods,  Crustacea,  Spiders,  and  Insects.  They  are  all 
characterized  by  the  possession  of  hollow  and  jointed 
organs  of  locomotion  provided  with  distinct  muscles, 
instead  of  the  mere  lateral  setae  or  bristles  often  met  with 
amongst  Yermes.  The  lowest  types  of  these  various 
classes  possess  a  nervous  system  closely  analogous  to 
that  of  the  various  kinds  of  Worms  ;  but  in  the  higher 
kinds  of  Crabs,  Spiders,  and  Insects,  we  meet  with  a 
great  increase  in  the  complexity  of  animal  organization, 
and  this  further  complexity,  as  might  have  been  expected, 
extends  to  the  nervous  system. 

Among  Insects,  for  example,  the  respiratory  organs 
assume  a  marvellous  degree  of  elaboration,  and  the  develop- 
ment of  this  system,  together  with  a  correlated  organiza- 
tion of  their  nervous  and  muscular  systems,  contributes 
greatly  to  confer  upon  these  denizens  of  the  air  those  enor- 
mous powers  of  locomotion  Ijr  which  they  are  remarkable. 
But  the  acuteness,  discriminative  power,  and  structural 
elaboration  of  sense-organs,  is  almost  sure  to  be  greatly 
increased  in  creatures  endowed  with  such  activity ;  and, 
looking  to  the  constitution  of  the  Brain  as  well  as  to 
the  nature  of  the  '  intelligence  '  of  these  lower  animals,  it 
may  easily  be  conceived  that  increased  sensorial  activity  is 


94 


THE  NERVOUS  SYSTEM  OF  ARTHROPODS. 


likely  to  be  associated  with  greater  brain  development  and 
with  higher  or  more  complex  brain  functions. 

Among  the  lower  Myriapods,  such  as  lulus  and  Geophi- 
lus,  in  wdiich  the  limbs,  though  very  numerous,  are  feeble 
and  ill-developed,  the  nervous  system  exhibits  only  a 
slight  advance  over  the  forms  which  it  presents  among 
the  higher  Annelida.  In  lulus  (fig.  33)  the  single 
abdominal  cord  shows  almost  no  traces  of  ganglionic 
swellings,  owing  to  the  great  number  of  the  small  nerves 
given  off  on  each  side,  along  its  entire  length,  which  are 
distributed  to  the  hundreds  of  small  segments  entering 
into  the  composition  of  the  body. 


Pio  33.— Anterior  part  of  the  Nervous  System  of  lulus  (Owen),  a,  a.  Cerebral 
ganglia ;  c,  c,  optic  nerves  ;  d,  d,  antcnnal  nerves ;  b,  nerves  of  the  paljiless 
mandibles  ;  g,  oesophageal  cords ;  e,  f,  stomato-gastric  nerves ;  h,  motor  nerves  to 
the  maxillse,  proceeding  from  the  part  wliich  corresponds  with  the  sub-oesophageal 
ganglia,  here  fused  with  i,  i,  the  ventral  cord. 


The  brain  (a,  a),  elongated  transversely,  is  divided  by  a 
slight  median  furrow,  and  is  continuous  with  the  short 
and  thick  optic  nerves  (c,  c).  Two  separate  nerves 
are  received   from  the  antenna)  on  each  side  [d,  d),  below 


Chap.  VI.l    THE   NERVOUS    SYSTEM   OF   ARTHROPODS.       95 

and  in  front  of  the  optic  nerves  ;  whilst  nearer  the  middle 
line  two  other  nerves  on  each  side  (b)  are  in  relation 
with  the  palpless  mandibles.  The  thick  oesophageal 
cords  (g)  are  continued  from  the  posterior  and  inferior 
angles  of  the  brain  ;  and,  as  they  descend  to  enter  the  me- 
dullary or  sub-oesophageal  ganglion  at  the  commencement 
of  the  ahdominal  cord  (i,  i),  they  are  united  by  a  cross 
branch,  as  in  many  Crustacea  (fig.  36).  From  this  sub- 
oesophageal  ganglion  large  nerves  are  given  off  on  each 
Bide  (h)  to  supply  the  maxillae  and  other  parts  about  the 
mouth. 

"  The  stomato-gastric  nerves,  which  arise  from  the 
posterior  part  of  the  brain  immediately,  form  a  third 
slender  ring  (e)  about  the  oesophagus,  from  the  middle  of 
the  upper  part  of  which  the  trunk  of  the  stomato-gastric 
system  (/)  is  continued  a  short  way  back  upon  the  stomach," 
when  it  divides  into  two  branches  which  "  bend  abruptly 
backwards,  and  run  parallel  with  each  other  along  the 
dorso-lateral  parts  of  the  wide  and  straight  alimentary 
canal."    (Owen.) 

In  the  more  powerful  predatory  Myriapods,  of  which 
the  common  Centipede  may  be  taken  as  a  type,  a  distinct 
advance  is  met  with.  This  carnivorous  creature  has  a 
smaller  number  of  better-developed  limbs,  and  its  nervous 
system  closely  resembles  that  found  amongst  the  larvae  or 
Caterpillars  of  higher  Insects  (fig.  39).  The  supra-oesopha- 
geal  ganglia,  or  brain,  receive  nerves  from  the  two  pairs  of 
antennas,  and  from  the  groups  of  ocelli  on  each  side  of  the 
head.  They  are  connected  by  oesophageal  cords  with  a 
bilobed  infra- oesophageal  ganglion,  which  distributes  nerves 
to  the  jaws  and  other  parts  about  the  mouth.  This  bilobed 
infra-cesophageal  ganglion  is  the  first  and  largest  of  a 
series  of  ventral  ganglia,  numbering  about  twenty,  wliicli 
are  connected  together  by  a  double  ventral  cord.     Every 


96 


THE    NERVOUS    SYSTEM    OF    ARTHROPODS. 


ganglion  sends  off  lateral  nerves  to  a  pair  ot  limbs.     The 
stomato-gastric   nerves   are  connected  with  the  posterior 
part  of  the  brain  or  with  the  oesopha- 
FiG.  3K         Fig.  35.       g^^j  ^^j.^^g^  ^^^  ^^^^^  distribute  them- 
selves over  the  alimentary  canal  in 
the  usual  manner. 


AmonsT    Crustacea 


great 


differ 


ences  are  met  with  in  the  degree  of 
concentration  of  the  nervous  system, 
the  variations  being,  in  the  main,  de- 
pendent upon  differences  of  external 
form  and  in  the  arrangement  of 
locomotor  appendages,  in  the  difierent 
representatives  of  the  class.  In  some 
of  the  lower  terms  of  the  series,  such 
as  the  Sandhopper  and  its  allies,  in 
which  the  body  is  elongated  and  com- 
posed of  many  almost  similar  seg- 
ments, the  nervous  system  is  not  very 
different  from  that  of  many  Worms. 
In  the  Sandhopper,  indeed,  the  ven- 
/'"dLiTZZ:::^  tral  cords  and  ganglia  (fig.  34)  of  the 
(Taiitrus  locusia).   (Grant.)  two  sides   of  tlio  body  are  separate 

Showing  separate    cerebral     „  ^ ,  , ,  •       r> 

ganglia,  each  about  the  same  "'om  ouc  another  as  they  are  in  Ser- 

size  as  other  ganglia  situated    p^J^    /fior^   32)       althouo-h    the    fj^anorlia 

on  the  separate  ventral  cords.    ^         ^  n  -  ^  ^       ^ 

Fig.  35.-Neivous  System  are  licre  fcwcr  111  iiumber  and  much 
more  distinct. 


of  Cymothoa.  (Grant.)  Cere- 
bral ganglia  almost  wholly 
absent  from  oesophageal 
ring.  Oesophageal  cords  dis- 
tinct, and  uniting  bclowjnto 
a  single  ventral  cord,  with 
compound  ganglia  at  inter- 
vals. 


several  ganglia  diminishes. 


In  slightly  higher  forms  of  Crus- 
tacea, however,  the  two  divisions  of 
the  originally  double  ventral  cord 
always  become  fused  together,  whilst, 
at  the  same  time,  the  equality  of  the 
T]ius,  in   such  forms  as  the 


Chap.  VL]    NERVOUS    SYSTEM    OF    ARTIlROrOLS. 


97 


Lobster  and  the  Crayfisb,  the  gangHa  of  the  thorax,  which 
supply  nerves  to  the  Hmbs,  are  distinctly  larger  than  those 
of  the  abdominal  segments,  though  these  are  also  of 
good  size,  since  the  tail-segments  are  actively  called  into 
play  during  locomotion. 

In  the  Prawn  a  further  development  and   concentration 
of  the  nervous  system  is  seen.     The 
fused  into  a  single  elliptical  mass,  whilst 


thoracic  ganglia  are 


^^^. 
^%^^^ 


those  of  the  abdominal  segments  still  re- 
main separate. 

But  in  the  ordinary  edible  Crab  (fig.  36) 
and  its  allies,  an  even  more  remarkable 
concentration  of  the  nervous  system  is  met 
with.  All  the  thoracic  and  all  the  abdo- 
minal ganglia  are  here  fused  into  one  large 
perforated  mass  of  nervous  matter  (c,  c), 
situated  near  the  middle  of  the  ventral 
region  of  the  body.*  From  this  large 
and  compound  ganglionic  mass  nerves  are 
received  from,  and  given  off  to,  the  limbs, 
to  the  abortive  tail,  and  to  other  adjacent 
parts.  The  brain  {ci)  of  the  Crab  is  repre- 
sented by  a  rather  small  bilobed  ganglion. 
It  receives  nerves  from  the  pedunculated 
compound  eyes,  from  the  two  pairs  of 
antennse,  and  from  the  palpi-bearing  man- 
dibles.    The  posterior  antennae  (or  anten-   ganglia     receiving 

optic,     tactile,     and 

nules,  as  they  are  sometimes  termed)  con-   olfactory  (?)  nerves ; 


Fig.  36.— Nervous 
System  of  a  Crab 
{Palinurus  vulgaris), 
a,     Fused    cerebral 


tain  in  their  basal  joint  a  body  which  is   l'^l'^°^^^\    ^eat 
supposed  to  represent  an  olfactory  organ,   ventral    ganglionic 
though  others  have   regarded  it   (on  very  ^ards.) 
insufficient  grounds)  as  an  organ  of  hear- 
ing.    This   small  bilobed  brain   is,   indeed,   thought    by 
*  A  large  artery  passes  through  the  aperture  in  this  ganglion. 


98  NERVOUS    SYSTEM   OF    ARTHROPODS. 

many  naturalists  really  to  embody  three  pairs  of  ganglia, 
in  relation  with  three  pairs  of  sensory  organs,  viz.,  eyes, 
tactile  antennae,   and  the  supposed  olfactory  antennules. 

The  brain  is  connected,  by  means  of  a  long  cord  ou 
each  side  (h,  h)  of  the  oesophagus,  with  the  anterior  ex- 
tremity of  the  great  ventral  ganglion.  Nerves  in  relation 
with  the  organs  of  mastication  join  the  cords  about  mid- 
w^ay  between  the  brain  and  the  great  abdominal  ganglion, 
and  small  ganglia  are  to  be  found  in  this  situation.  Just 
behind  these  small  ganglia  a  transverse  commissure  con- 
nects the  cords  with  one  another.  The  unusual  length  of 
the  oesophageal  cords  is  one  of  the  most  notable  character- 
istics of  the  nervous  system  of  the  higher  Crustacea,  and 
this  seems  due  in  part  to  the  fact  that  the  sub- oesophageal 
ganglia  remain  separate  instead  of  uniting  with  one 
another,  as  they  do  in  fig.  18. 

The  '  stomato-gastric '  system  of  Crustacea  is  very 
similar  to  that  which  exists  in  Centipedes.  One  part  of  it 
is  given  off  from  the  oesophageal  cord  on  each  side,  while 
another  median  branch  proceeds  from  the  posterior  part  of 
the  united  cephalic  ganglia,  as  in  lulus  (fig.  33,  /).  Where 
the  main  nerve  lies  on  the  upper  surface  of  the  stomach, 
in  the  higher  Crustacea,  it  is  connected  with  one  or 
two  ganglia  from  which  branches  pass  to  the  walls  of  this 
organ.  They  send  filaments  also  to  the  right  and  left, 
into  the  liver.  This  principal  visceral  nerve  is  brought 
into  communication  with  the  above-mentioned  nerves, 
going  to  the  organs  of  mastication,  by  means  of  two 
filaments  which  join  the  ganglionic  swellings  on  the 
oesophageal  cord  at  the  part  whence  they  issue. 

Among  Arachnida  forms  of  the  nervous  system  exist 
which  agree  in  many  respects  with  those  belonging  to 
members  of   the   class   last   described — especially   where 


Chap.  VI.]     NERVOUS    SYSTEM    OF    ARTHROPODS.  99 

there  are  general  similarities  in  the  external  configuration 
of  the  body.  Thus  in  Scorpions  the  arrangement  of 
the  nervous  system  is  not  very  dissimilar  from  that  met 
with  in  the  Prawn  and  its  allies.  The  thoracic  ganglia 
have  coalesced  with  one  another  and  with  the  anterior 
abdominal  ganglia;  thereby  forming  a  large  stellate  ner- 
vous mass  which  supplies  the  limbs  and  the  anterior  part  of 
the  abdomen.  The  ventral  cord  throughout  the  remainder 
of  the  abdomen,  and  its  caudal  prolongation,  is  marked  at 
intervals  by  a  series  of  small  ganglionic  swellings. 

In  Spiders  proper,  the  nervous  system  attains  its  maxi- 
mum amount  of  concentration.  The  bilobed  brain  (fig.  37,  c) 
receives  nerves  on  each  side  (o),  corresponding  in  number 
with  the  ocelli  which  the  animal  may  happen  to  possess. 


Fig.  S7.— Head  and  Nervous  System  of  a  Spider  [MijgaU).  (Owen  after  Du^^s.) 
c,  Cerebral  ganglia  (side  view),  receiving  (oi  optic  nerves,  and  {m)  nerves  (sensor j-  and 
motor)  from  the  ijowerful  mandibles,  m'.  The  cerebral  ganglia  are  connected  by- 
very  short  CBSoi^hageal  cords  with  a  large  stellate  ventral  ganglion  (,«),  from  which 
five  large  nerves  issue  on  each  side  (p,  I,  I);  o,  mouth;  b,  oesophagus  ;  d,  stomach. 

It  also  receives  two  large  nerves  {m),  which  probably  con- 
tain outgoing  as  well  as  ingoing  fibres,  from  the  so-called 
mandibles  {in). 

Owing  to  the  suctorial  habits  of  these  fierce  and 
predatory  creatures,  the  oesophagus  is  very  iiari-ow  ;  and 
as  a  consequence,  the  oesophageal  cords  are  very  f  hort,  so 
that  the  brain  is — unlike  the  arrangement  which  ultains 


100 


NERVOUS    SYSTEM    OF    ARTHROPODS. 


in  the  common  Crab  and  its  allies  (fig.  36) — quite  close 
to  the  great  stellate  sj^stemic  ganglion  (s),  into  which 
are  fused  the  representatives  of  the  suh-oesophageal,  the 
thoracic,  and  the  abdominal  ganglia. 

From  this  ganglion  (fig.  38,  i) 
five  principal  nerves  are  sent  off 
on  each  side,  "  the  first  to  the 
pediform  maxillary  palpi;  the 
second  to  the  more  pediform 
labial  palpi,  which  are  usually 
longer  than  the  rest  of  the  legs, 
and  used  by  many  Spiders  rather 
as  instruments  of  exploration 
than  of  locomotion  ;  the  three 
posterior  nerves  supply  the  re- 
maining legs,  which  answer  to 
the  thoracic  legs  of  hexapod 
Insects."     (Owen.) 

Since  the  sub  -  oesophageal 
ganglia  are  in  part  analogous, 
as  already  stated,  with  the  '  me- 
dulla oblongata'  of  vertebrate 
animals,  their  fusion  with  the 
thoracic  ganglia  in  Arachnida, 
as  well  as  in  Myriapoda,  tends, 

Fig.    38. — Nervous    System    of   a  .  .  />  j.i 

great    scorpion-like    Spider    {Thehj-  m    a     mCaSUrC,     tO     COUlirm     thO 

phoHu.u'uadaUs).  (Gegonbauer,  after  yj^^^y  1^q\([  ]jy  c^^^j^q  aUatomistS, 
Blaiiclian).)     s,  Cerebral  ganglia  ;  /,  .       .       ,  ' 

greatventral  ganglion,  comnumicat-  that    it    is    better    tO     regard     tllC 

ing  with  five  large  nerves  on  eaeh    ^nicdulla'    aS    a   proloUgatioU    of 

Mflc ;  0,  eyes;  p,  palpi;  2'  2'^'',  lect ;  ■••  " 

c,  tail-like  prolong  itiun.  tlic  spiual  cord,  than  as  an  in- 

tegral part  of  the  brain.  The 
artificial  line,  that  is,  which  for  convenience  is  drawn 
between  the  brain  and  the  cord  in  Vertebrates,  should  be 
placed  at  the   upper  rather  than  the  lower   or  posterior 


Chap.  VI.]     NERVOUS    SYSTEM    OF    ARTHROPODS.  101 

boundary  of  the  '  medulla,'  so  tliat  the  latter  part  may 
be  regarded  as  the  more  highly  developed  portion  of  the 
spinal  cord  by  which  fusion  with  the  hrain  is  effected. 

The  visceral  nerves  are  well  developed  in  the  higher 
Arachnida.  They  consist  of  one  or  two  filaments,  on 
which  a  ganglion  may  exist,  in  connection  with  the  posterior 
part  of  the  brain,  and  thence  proceeding  to  the  stomach 
and  other  internal  organs.  There  are,  moreover,  two  or 
three  branches  given  off  from  the  great  ventral  ganglion 
which,  after  passing  through  smaller  ganglia,  distribute 
numerous  filaments  to  the  intestines,  the  respiratory 
and  genital  organs,  as  well  as  other  viscera.  The  former 
set  may  be  in  the  main  afferent,  and  the  latter  perhaps 
principally  efferent  visceral  nerves. 

Organs  of  vision  are  much  more  elaborate  in  Crustacea, 
Spiders  and  Insects,  than  among  Worms  or  Centipedes. 
And,  whilst  organs  of  touch  and  taste  are  further  perfected, 
two  sensory  endowments,  found  among  higher  Mol- 
lusks,  seem  also  to  manifest  themselves.  These  higher  Ar- 
thropods are  capable  of  being  impressed  by,  and  of  discri- 
minating, the  different  odours  of  some  substances  anterior 
to  their  contact  with  the  mouth.  This  power  must  mate- 
rially aid  them  in  their  '  search '  for  or  recognition  of  food. 
Some  Arthropods  seem  to  be  also  capable  of  appreciating 
those  vibrations  of  the  medium  they  inhabit  which  induce 
impressions  recognizable  by  us  as  sounds  or  noises.  Still, 
in  some  of  the  most  highly  organized  forms  of  Insects 
a  sense  of  hearing  appears  to  have  no  existence.  Much 
uncertainty,  in  fact,  exists  in  regard  to  this  sense-endow- 
ment.* Extreme  sensibility  of  the  tactile  order  may 
cause  the  organism  to  display  an  apparent  sensitiveness 
to  sounds.  A  delicate  general  ability  to  appreciate  aerial 
vibrations,  therefore,  must  not  be  confounded  with  the 
*  See  pp.  65  and  205. 


102 


:nervous  system  of  arthropods. 


more  special   auditory  perception.      On  the   other  hand, 
it  is  quite  possible    that  sounds  not  appreciable  by  our 


Fig.  40. 


U' 


7 


Fig.  39.— Nervous  System  of  full-grown  Catei-pillar  of  Privet  Hawk-Moth  (Sphinx 
igustri),  about  two  days  previous  to  its  change  to  the  chrysalis  state. 

Fig.  40.— Nervous  System  of  the  Privet  Ilawk-Moth  thirty  days  after  changing  tc 
the  chrysalis  state.  The  abdominal  cords  are  now  seen  to  be  much  shortened,  ano 
bearing  five  instead  of  seven  gangha. 

fio.  41.— Nervous  System  of  the  perfect  Insect,  a,  Greatly  enlarged  cerebral, 
and  B,  optic  ganglia.  The  numerals  refer  to  the  numbers  of  the  gJinglia.  o,  o,  o,  o; 
respiratory  nerves,  '  ncrvi  transvcrsi.'     (Solly  after  Newport.) 

organization    may  be  perceptible  by  the   sensory  organs 
and  centres  of  some  of  the  lower  organisms. 

Additional  sensory  endowments  like  Smell  and  Hearing 


Chap.  VI.]    ^lERVOUS    SYSTEM    OF    ARTHROPODS.  103 

would,  of  course,  be  of  importance  to  any  organisms,  but 
more  especially  to  those  possessing  active  powers  of  loco- 
motion. They  would  serve,  on  the  one  hand,  to  assist  in 
bringing  their  possessors  into  relation  with  food,  or  with 
sexual  mates,  and,  on  the  other,  to  warn  them  of  the 
approach  of  enemies. 

The  nervous  system  of  Insects  varies  not  only  among 
different  classes  and  orders,  but  even  in  the  same  indivi- 
dual in  different  stages  of  its  development.  The  cater- 
pillar of  a  Moth  (fig.  39)  or  Butterfly  presents  a  nervous 
system  not  very  different  from  that  met  with  in  the 
Centipede;  \^jhile  in  the  imago 
or  perfected  Insect,  the  same 
system  has  undergone  some  re- 
markable changes — there  is,  for 
instance,  an  increased  size  of 
the  cerebral  ganglia,  and  also  a 
notable  development  of  some  of 
the  ganglia  pertaining  to  the 
ventral  cord,  while  concentra- 
tion or  even  suppression  of 
others  is  met  with. 

1        •  1  -r>    J.J.  Fig.  42.— Brain  and  Adjacent  Parts 

in      such     m sects      as     Butter-     of    Nervous     System    of     a    rather 

flies.    Bees,    Dragon-flies,    and  '^""ssi^^'  ^pt«^°^«  ^l'\^^'  3;;^"'«^-^''« 

'  '  °    ^  tenebricosa.    (iNevrport.)  a,  Bram  re- 

OtherS    where    the    visual    organs     ceMng  the  antennal  nerves,  and  also 

,         T         1  T  ;i     B,  the  optic  nerves  ;   c,  origin  of  the 

are   enormously  developed,  and   ,y  ^ipathetic  from  and  rear  the  com - 

in     which  the  power  of   vigorous     mencement  of  the  ^bophageal  cords ; 

*■      ,  .  D,  the  sub-ojsophageal  ganglia;  6,  the 

and     sustained    flight     is     COrreS-    vagus,  or  visceral  nerve  before  reach- 

pondingly  increased,  the  nervous  '-^  ''^  ^'-^^i^"'  ''  '^'''''  ''''''''' 

r  n  .J  '  nerves. 

system  as  a    whole  attains    its 

maximum  of  development  among  the  Arthropoda.  The 
brain  of  these  creatures  difl'ers  from  that  existing  in  all 
other  members  of  the  class  by  reason  of  the  great  develop- 


104      NERVOUS  SYSTEM  OF  ARTHROPODS. 

ment  of  those  portions  of  it  in  relation  with  the  \isual 
organs,  as  may  be  seen  by  fig.  45,  representing  the  nervous 
system  of  the  Common  Fly,  and  by  fig.  42,  representing 
the  brain  of  a  Beetle.  A  ganglionic  swelling  is  fre- 
quently found  where  the  optic  nerve  joins  the  brain,  and 
in  some  Insects  there  are  also  small  ganglionic  swellings 
at  the  corresponding  parts  of  the  antennal  nerves. 

It  is  in  Ants,  Bees,  and  Flies,  however,  that  the  brain 
of  Insects  seems  to  attain  its  greatest  development.  Speak- 
ing of  the  brain  of  the  Blow-fly,  B.  T.  Lowne  says* : — 
"  Next  to  bees  and  ants  that  of  the  blow-fly  is  the  largest 
known  in  any  insect  proportionally  to  its  size,  being  about 
thirty  times  larger  than  the  cephalic  ganglia  of  the  larger 
beetles."  The  same  writer  adds  : — "  But  a  more  positive 
indication  of  a  higher  type  of  organization  than  even  the 
relative  bulk  of  the  sensory  ganglia  is  found  in  the  fact 
that  two  very  remarkable  convoluted  nerve  centres,  con- 
nected by  a  commissure,  each  about  l-30th  of  an  inch  in 
diameter,  surmount  the  cephalic  ganglion,  and  are  con- 
nected to  it  by  a  pair  of  distinct  peduncles ;  f  these  are 
extremely  like  the  pedunculated  convoluted  nerve  centres 
which  occupy  the  same  position  in  bees  and  ants,  first 
described  by  M.  Felix  Dujardin  ("  Ann.des  Sc.  Nat."  (Ser. 
iii.),  t.  xiv.  p.  195),  and  considered  by  him  as  analogous  to 
the  cerebral  lobes  of  the  higher  animals.  That  naturalist 
failed  to  distinguish  these  organs  in  the  fly,  probably 
owing  to  their  being  imbedded  in  the  substance  of  the 
cephalic  ganglion."  In  the  Bee,  according  to  Dujardin, 
these  peculiar  bodies  are  attached  to  the  sensory  ganglia 
by  a  single  peduncle,  and  their  united  bulk  is  said  by 
him  to  equal  -g-th  of  the  whole  brain.  Farther  details 
concerning  these  interesting  structures  are  much  needed. 
The  double  cerebral  ganglion  is  connected  in  nearly 
*  "  Anat.  of  the  Blow-fly,"  p.  14        f  Loc  cit.,  PI.  vii.  tig.  4. 


Chap.  VL]    NERVOUS    &YSTEM    OF    ARTHROPODS. 


105 


all  Insects  with  a  separate  sub-oesopliageal  ganglion,  from 
which  nerves  are  given  off  to  the  mandibles,  the  maxillae, 
and  the  labium.  But,  as  in  Spiders,  the  oesophageal  ring  is 
often  very  narrow,  owing  to  the  greatly  diminished  size  of 
the  oesophagus  in  the  imago  forms  of  higher  Insects.  In 
Spiders    and  Myriapods,   as   before  stated,  the  sub-oeso- 


FiG.  43. 


Fig.  44. 


Fig  45 


>^^ 


Fig.  43.— Nervous  System  of  a  White  Ant  ( Termes).   (Gegenbauer  after  Lesp^s.) 

Fig.  44.— Nervous  System  of  a  Water  Beetle  (Dutiscus).     (Gegenbauer.) 

Fig.  45.— Nervous  System  of  a   Fly  (3Iusca\     (Gegenbauer  after  Blancbard.)    o. 

Eyes  ;  g.%  supra-oesophageal  ganglia  (brain)  ;  gi,  sub-oesophageal  ganglion  ;  yr,  g'^,  <j^ 

fused  ganglia  of  tlie  tliorax. 

phageal   ganglion  has   no  separate  existence   apart  from 
the  thoracic  ganglia. 

In  many  Insects  the  three  thoracic  ganglia  preserve 
a  separate  existence  (fig.  43),  though  in  others  of  the 
higher  types  above  referred  to  these  ganglia  are  more 
frequently  fused  into  a  single  lobed  mass  (fig.  45).     The 


106  NERVOUS    SYSTEM    OF    ARTHROPODS. 

eight  abdominal  ganglia,  which  are  always  much  smaller 
than  the  thoracic,  also  continue  to  have  a  separate  exist- 
ence among  some  of  the  less  developed  tj])es  of  Insects 
(fig.  43)  though  it  is  more  frequent  for  some,  or  even  all, 
of  them  to  disappear  (figs.  44,  45). 

The  '  stomato-gastric '  system  of  nerves  attains  a  con- 
siderable degree  of  complexity  in  these  animals.  In  front 
there  is  a  median  ganglion  (fig.  42)  lying  below  and  often 
anterior  to  the  brain.  This  oral  ganglion  is  a  swelling 
situated  on  the  great  median  (afferent)  visceral  nerve,  at 
the  spot  where  it  bifurcates  in  order  to  proceed  to  each 
half  of  the  brain.  It  receives  branches  from  the  mouth 
and  adjacent  parts.  The  main  nerve,  or  else  the  ganglion, 
is  also  connected  with  other  branches  (c),  proceeding  from 
one  or  two  pairs  of  lateral  ganglia  situated  close  to  the 
oesophageal  cords,  and  often  in  structural  relation  with 
them.  This  visceral  system  of  nerves  receives  branches 
from  the  stomach,  the  intestines,  and  other  internal 
organs. 

In  Insects,  moreover,  we  meet  with  another  semi- 
independent  set  of  visceral  nerves,  connected  with  a  chain 
of  minute  ganglia  lying  upon  the  great  ventral  ganglionated 
cord,  and  united  thereto  by  means  of  minute  nerve  fila- 
ments. The  nerves  (fig.  41,  o,  o,  o)  in  connection  with  this 
chain  of  minute  ganglia  are  received  from  and  distributed 
to  the  all-pervading  respiratory  organs  (air  tubes)  of  the 
Insect.  They  are  known  to  anatomists,  on  account  of  the 
disposition  of  their  main  branches,  as  '  nervi  transvcrsi,' 
and  are  much  more  highly  developed  in  these  animals 
than  are  anything  corresponding  to  them  amongst  other 
Arthropods. 


CHAPTER  Vn. 

DATA  CONCERNING  THE  BRAIN  DERIVED  FROM  THE  STUD-J 
OF  THE  NERVOUS  SYSTEM  OF  INVERTEBRATES. 

This  survey  of  some  of  the  principal  varieties  of  the 
Nervous  System  among  the  Invertebrata,  brief  though  it 
has  been,  should  have  sufficed  to  call  attention  to  many 
important  facts  and  to  show  the  warrant  for  certain  related 
inferences,  many  of  which  are  embodied  in  the  following 
propositions  : 

1.  Sedentary  animals,  though  they  may  possess  a 
Nervous  System,  are  often  headless,  and  they  then  have 
no  distinct  morphological  section  of  this  system  answering 
to  what  is  known  as  a  Brain. 

2.  Where  a  Brain  exists,  it  is  invariably  a  double 
organ.  Its  two  halves  may  be  separated  from  one 
another ;  though  at  other  times  they  are  fused  into  what 
appears  to  be  a  single  mass. 

3.  The  component  or  elementary  parts  of  the  Brain 
in  these  lower  animals  are  Ganglia  in  connection  with 
nerves  proceeding  from  special  impressible  parts  or  Sense 
Organs ;  and  it  is  through  the  intervention  of  these  united 
Sensory  Ganglia  that  the  animal's  actions  are  brought  into 
harmony  with  its  environment  or  medium. 

4.  That  the  Sensory  Ganglia,  which  in  the  aggregate 
constitute  the  Brain  of  invertebrate  animals,  are  connected 


108  THE    BRAIN    OE    INVERTERTIATES. 

with  one  another  on  the  same  side  and  also  with  their 
fellows  on  opposite  sides  of  the  body.  They  are  related 
to  one  another  either  by  what  appears  to  be  continuous 
growth  or  by  means  of  *  commissures.' 

5.  The  size  of  the  Brain  as  a  whole,  or  of  its  several 
parts,  is  therefore  always  fairly  proportionate  to  the  develop- 
ment of  the  animal's  special  Sense  Organs.  The  more 
any  one  of  these  impressible  surfaces  or  organs  becomes 
elaborated  and  attuned  to  take  part  in  discriminating 
between  varied  external  impressions,  the  greater  will  be 
the  proportionate  size  of  the  ganglionic  mass  concerned. 

6.  Of  the  several  sense-organs  and  Sensory  Ganglia 
who;->e  activity  lies  at  the  root  of  the  Instinctive  and 
Intelligent  life  (such  as  it  is)  of  Invertebrate  Animals, 
some  are  much  more  important  than  others.  Two  of 
them  especially  are  notable  for  their  greater  proportional 
development  :  viz.,  those  concerned  with  Touch  and 
Vision.  The  organs  of  the  former  sense  are,  however, 
soon  outstripped  in  importance  by  the  latter.  The  visual 
sense,  and  its  related  nerve-ganglia,  attain  an  altogether 
exceptional  development  in  the  higher  Insects  and  in  the 
highest  Mollusks. 

7.  The  sense  of  Taste  and  that  of  Smell  seem,  as  a 
rule,  to  be  developed  to  a  much  lower  extent.  In  the 
great  majority  of  Invertebrate  Animals  it  is  even  difficult  to 
point  to  distinct  organs  or  impressible  surfaces  as  certainly 
devoted  to  the  reception  of  either  of  such  impressions. 
Nevertheless,  as  we  shall  subsequently  find,  there  is  reason 
to  believe  that  in  some  Insects  the  sense  of  Smell  is  mar- 
vellously keen,  and  so  much  called  into  play  as  to  make  it 
for  such  creatures  quite  the  dominant  sense  endowment. 
It  is  pretty  acute  also  in  some  Crustacea. 

8.  The  sense  of  Hearing  seems  to  be  developed  to  a  very 
slight  extent.     Organs  supposed  to  represent  it  have  been 


CnAP.  VII.]       THE    BRAIN    OF    INVERTEBRATES.  109 

discovered,  principally  in  Mollusks  and  in  a  few  Insects. 
It  is,  however,  of  no  small  interest  to  find  that  where  these 
organs  exist,  the  nerves  issuing  from  them  are  most  fre- 
quently not  in  direct  relation  with  the  Brain,  but  imme- 
diately connected  with  one  of  the  principal  motor  nerve- 
centres  of  the  body.     It  is  conjectured  that  these  so-called 

*  auditory  saccules '  may,  in  reality,  have  more  to  do  with 
what  Cyon  terms  the  sense  of  Space  than  with  that  of 
Hearing  (p.  218).  The  nature  of  the  organs  met  with 
supports  this  view,  and  their  close  relations  with  the  motor 
ganglia  also  become  a  trifle  more  explicable  in  accord- 
ance with  such  a  notion. 

9.  Thus  the  associated  ganglia  representing  the  double 
Brain  are,  in  animals  possessing  a  head,  the  centres  in 
which  all  impressions  from  sense-organs,  save  those  last 
referred  to,  are  directly  received,  and  whence  they  are 
reflected  on  to  diff'erent  groups  of  muscles — the  reflection 
occurring  not  at  once  but  after  the  stimulus  has  passed 
through  certain  *  motor'  ganglia.  It  maybe  easily  under- 
stood, therefore,  that  in  all  Invertebrate  Animals  perfection 
of  sense-organs,  size  of  brain,  and  power  of  executing 
manifold  muscular  movements,  are  variables  intimately 
related  to  one  another. 

10.  But  a  fairly  parallel  correlation  also  becomes  estab- 
lished between  these  various  developments  and  that  of  the 
Internal  Organs.  An  increasing  visceral  complexity  is 
gradually  attained ;  and  this  carries  with  it  the  necessity 
for  a  further  development  of  nervous  communications. 
The  several  internal  organs  with  their  varying  states  are 
gradually  brought  into  more  perfect  relation  with  the 
principal  nerve  centres  as  well  as  with  one  another. 

11.  These  relations  are  brought  about  by  important 
visceral  nerves  in  Vermes  and  Arthropods — those  of  the 

*  Stomato- Gastric  System  ' — conveying  their  impressions 

6 


110  THE    BRAIN    OF    INVERTEBRATES. 

either  direct  to  the  posterior  part  of  the  Brain  or  to  its 
peduncles.  They  thus  contribute  internal  impressions 
which  impinge  upon  the  Brain  side  by  side  with  those 
coming  through  external  sense  organs. 

12.  This  Visceral  System  of  Nerves  in  invertebrate  ani- 
mals has,  when  compared  with  the  rest  of  the  Nervous 
System,  a  greater  proportional  development  than  among 
vertebrate  animals.  Its  importance  among  the  former  is 
not  dwarfed,  in  fact,  by  that  enormous  development  of  the 
Brain  and  Spinal  Cord  which  gradually  declares  itself  in 
the  latter. 

13.  Thus  impressions  emanating  from  the  Viscera  and 
stimulating  the  organism  to  movements  of  various  kinds, 
whether  in  pursuit  of  food  or  of  a  mate,  would  seem  to 
have  a  proportionally  greater  importance  as  constituting 
part  of  the  ordinai-^^  mental  life  of  Invertebrate  Animals, 
The  combination  of  such  impressions  with  the  sense- 
guided  movements  by  which  they  are  followed,  in  complex 
groups,  will  be  found  to  afford  a  basis  for  the  development 
of  many  of  the  Instinctive  Acts  which  animals  so  fre- 
quently display. 


CHAPTER  VIII. 

THE   BRAIN   OF   FISHES   AND   OF   AMPHIBIA. 

In  all  Vertebrates  the  relation  of  the  principal  nervous 
ganglia  to  the  commencement  of  the  alimentary  canal  is 
different  from  that  existing  among  the  Invertebrates. 
We  no  longer  find,  as  in  the  Mollusk,  the  Worm,  or  the 
Insect  a  ring  of  nerve  matter  encircling  the  CEsophagus. 
The  parts  which  in  Fishes  answer  to  the  supra-  and  sub- 
oesophageal  ganglia  lie  altogether  above  the  oesophagus, 
and  they  are,  moreover,  directly  continuous  with  one 
another,  instead  of  being  connected  by  long  or  short  com- 
missures. 

In  Fishes,  as  well  as  in  other  Vertebrates,  all  the  parts 
constituting  the  Brain,  as  well  as  the  Medulla  Oblongata, 
are  enclosed  within  a  distinct  '  skull'  or  '  cranium,'  while 
within  this  they  are  again  surrounded  by  two  membranes 
— one  of  which,  and  the  thicker  of  the  two.  Hues  the 
inner  surface  of  the  cranium  ;  while  the  other,  which  is 
delicate  and  transparent,  immediately  envelops  the  £>Teat 
nerve  centres.  The  Spinal  Cord,  which  is  directly  con- 
tinuous with  the  Medulla,  is  also  lodged  in  a  bony  case 
known  as  the  '  spinal  canal'  ;  and  this  is  formed  by  the 
contiguous  posterior  arches  of  the  several  vertebra)  com- 
posing the  spine  or  vertebral  column. 

Among   the   Invertebrata,    it   is    the    nervous    system 


112  THE    BRAIN    OF    FISHES 

of  Insects  and  other  Arthropods  which  approaches  most 
closely  to  that  of  Fishes,  inasmuch  as  they  possess  a 
single  or  double  ganglionated  nervous  cord  running  through 
the  body,  which  is  fairly  comparable  with  the  spinal  cord. 
In  Insects  and  their  allies,  however,  this  cord  is  situated 
in  the  ventral  region ;  while  the  spinal  cord  of  Verte- 
brates lies  above  the  alimentary  canal  in  the  dorsal  region 
of  the  body.  No  such  structure  exists  or  is  needed 
among  MoUusks,  because  these  organisms  have  no 
articulated  locomotor  appendages,  and  are  otherwise 
notably  different  in  form  and  organization ;  yet  it  is  true 
that  among  the  highest  representatives  of  this  latter 
class  (viz.,  the  Cephalopods),  we  get  the  first  approach  to 
the  formation  of  a  distinct  brain  case  or  '  cranium.' 

All  the  nerve-centres  situated  within  the  cranium  have 
been  regarded  as  parts  of  the  Brain  in  Vertebrates,  whilst 
those  lying  beyond  it,  and  within  the  spinal  canal,  con- 
stitute the  Spinal  Cord  :  the  two  together  are  sometimes 
spoken  of  as  the  '  Cercbro- Spinal  Axis.' 

But  in  addition  to  the  Sensory  Ganglia,  and  the  Medulla 
Oblongata,  there  are  certain  highly  important  supple- 
mentary parts  entering  into  the  composition  of  the  Brain  of 
the  Fish.  There  is,  for  instance,  a  pair  of  bodies  known 
as  the  Cerebral  Lobes ;  whilst  further  back,  in  connec- 
tion with  the  Medulla,  we  have  another  new  nervous 
ganglion,  single,  but  having  equal  parts  on  each  side  of 
the  middle  line,  which  is  known  as  the  Cerebellum. 
That  representatives  of  these  parts  (seemingly  superadded 
to  the  brain  of  Fishes  and  other  Vertebrates)  are  really 
non-existent  in  the  highest  Mollusks  and  Insects  it  would 
not  be  safe  to  affirm  ;  especially  as  ganglia,  which  have 
been  compared  to  Cerebral  Lobes,  exist  in  the  Cuttlefish, 
and  even  more  distinctly  in  Ants,  Bees  and  some  Flies. 
On    the  other  hand,  both   the    Cerebral  Lobes  and  tho 


Chap.  VIII.] 


AND    OE    AMPHIBIA. 


113 


Cerebellum  tend  to  increase  in  size  and  become  more 
and  more  complex  as  we  pass  from  Fishes  to  Reptiles, 
from  Reptiles  to  Birds,  and  from  Birds  to  Mammals. 

llie  relative  size  of  these  parts,  however,  as  well  as  of 
other  divisions  of  the  Brain,  will  be  found  to  vary  greatly 
in  different  kinds  of  Fishes. 


Fig.  46.— Brain  and  Cranial  Nerves  of  the  Perch,  side  view.  (Gegenbaner,  after 
Cuvier.)  A,  Cerebral  lobe  with  olfactory  ganglion  in  front ;  B,  optic  lobe  :  C,  cere- 
bellum ;  B,  medulla  oblongata ;  /,  olfactory  nerve  coming  from  a,  the  nasal  sac  ; 
//,  optic  nerve  cut  across  ;  ///,  oculo-motor  ;  IV,  trochlear  nerve  ;  V,  trigeminal  ; 
VII,  auditory ;  VIII,  vagus,  with  its  ganglion  ;  k,  lateral  branch  of  the  vagus  ; 
/,  upper  twig  of  the  same  ;  ;,i,  dorsal  branch  of  the  trigeminus,  which  is  joined  by 
n,  the  dorsal  branch  of  the  vagus  ;  a,  p,  y,  three  branches  of  the  trigeminus  ;  Be, 
facial  nerve  •-  X,  bronchial  branches  of  the  vagus. 


The  Spinal  Cord  of  Fishes  is  more  or  less  cylindrical  in 
shape  (fig.  47,  h)  and  almost  uniform  in  thickness  through- 
out, except  that  it  tapers  to  a  point  posteriorly.  It  occurs 
only  rarely  that  there  is,  as  in  the  Ray,  a  slight  swelling 
in  the  region  where  the  nerves  from  the  great  pectoral  fins 


114 


THE    BRAIN    OF    FISHES 


are  received,  and  sent  forth.  From  the  whole  length  of 
the  spinal  cord  a  series  of  nerves  is  given  off  on  each 
side,  and  each  of  them  is  connected  therewith  by  an  ante- 
rior (or  motor)  and  a  posterior  (or  sensory) 
root,  the  latter  swelling  into  a  more  or 
less  distinct  ganglion  just  where  its  fibres 
begin  to  mingle  with  those  of  the  anterior 
root.  This  mode  of  connection  of  the 
spinal  nerves  with  the  spinal  cord  exists 
throughout  the  class  of  Fishes  and  also 
in  all  other  Vertebrates. 

Anteriorly  the  cord  is  continuous  with 
a  slightly  more  swollen  prolongation — the 
before-mentioned  Medulla  Oblongata 
(fig.  47,  d).  Many  very  important  nerves, 
to  which  reference  will  subsequently  be 
made,  are  attached  to  this  part. 

Growing  from  the  back  of  the  anterior 
extremity  of  the  medulla  is  a  semi-ovoid 
or  tongue-like  projection,  which  has  been 
already  referred  to  as  the  Cerebellum. 
Though  single  in  appearance,  it  is  really 
double  and  composed  of  two  symmetrical 
halves.  No  distinct  connection  of  nerves 
with  this  body  can  be  detected  by  the  naked 

Fig.   47,— Brain  of    „„„ 
the  Pike,     a,  Olfac-      -^ 

tory  ganglia ;  b,  ce-       The   ccrebellum    cxists  in   its   simplest 

rebral  lobes ;  c,  OT)tic     o  •^i  'j^-      r^      ^       t  '        ,^ 

lobes;  E.cerebeiium;  ^^^"^  "^  the  parasitic  Cyclostomcs,  HI  the 
H,  spinal  cord;  x,  Sturgcou,  aud  also  iu  Polypterus  and  Le- 

olfactory  nerve,  di-  . 

viding  and  penetrat-  pidosn'cu,  where  it    appears  merely   as  a 

il.":^t;r\soi:  si^^^Ple  b^-i^^g^  ^^'  commissure,  crossing  the 

ly.j  anterior  and  upper  part  of  the    medulla. 

In  most  osseous   Fishes  it  is  larger,  and 

projects  backwards  over  the  medulla  in  the  form  of  a 


Chap.  VIIL") 


AND    OF    AMPHIBIA. 


115 


smooth,  convex,  semi-ovoid,  or  tongue-like  body  (fig.  49,  d). 
According  to  Professor  Owen,  the  cerebellum  is  *'  very  small 
in  the  lazy  Lump-fish,  and  extremely  large  in  the  active 
and  warm-blooded  Tunny."  It  attains  its  highest  develop- 
ment, however,  in  Sharks  (fig.  48,  c).  In  these  most  active 
and  predaceous  fishes  the  cerebellum  not  only  covers  much 
of  the  medulla,  but  advances  forwards  over  the  optic  lobes, 
and  the  extent  of  its  surface  is  further  increased  by  the 
existence  of  numerous  superficial  folds  or  indentations. 
In  front  of  the  cerebellum  are  two  rounded  ganglia  known 


Fig.  48. 


Fia.  49 


Fig.  48.  —Brain  of  the  Shark  (Carcharias) ,  side  view.  (OwenO  p,  Cerebral  hemi- 
sphere ;  o,  optic  lobe  ;  c,  cerebellum  with  surface  folds  (m) ;  r,  olfactory  ganglion, 
giving  off  (1)  olfactory  nerves  ;  z,  junction  of  olfactory  peduncle  with  cei'ebral  lobe  ; 
X,  Cms  cerebri ;  w,  pineal  body  ;  «,,  hypoaria  ;  j?,  pituitary  body  ;  2,  optic  nerve  ; 
8,  oculo-motor  nerve  ;  5,  trigeminus  ;  7,  auditory  ;  8,  vagus. 

Fig.  49. — Brain  of  Roach,  a,  Olfactory  peduncles  ;  b,  cerebral  lobes  ;  c,  opticlobes; 
d,  cerebellum  ;  e,  medulla  ;  /,  oiitic  nerves.     (After  Spurzheim.) 

as  the  Optic  Lobes  (fig.  49,  c),  which  correspond  with 
the  principal  part  of  the  Insect's  brain.  The  optic  nerves 
are  connected  with  their  under  surface  ;  and  they  decussate 
(figs.  51,  57),  so  that  the  one  proceeding  from  the  right  eye 
passes  to  the  left  optic  lobe,  and  that  from  the  left  eye  to 
the  right  optic  lobe.  This  new  kind  of  cross  arrangement 
will,  in  a  later  chapter,  be  referred  to  in  detail,  since,  with 
slight  differences,  it  also  exists  in  other  Vertebrates,  and, 
moreover,  seems  gradually  to  extend  to  other  parts  of 
the  nervous  system. 


116 


THE    BRAIN    OF    FISHES 


In  many  of  the  lower  Fishes  the  eyes  are  very  rudimen- 
tary. In  the  young  Lamprey  two  pigment  spots  replace 
the  single  '  eye  spot '  of  the  Lancelot.  In  the  genus 
Myxine  the  eyes  are  represented  hy  small  bodies,  which, 
though  in  connection  with  slender  optic  nerves,  are 
covered  over  by  muscle  as  well  as  by  skin.  The  ocular 
muscles  for  moving  the  eyeball  are  absent  in  many  Fishes  ; 
this  is  the  case  even  in  the  Gar-Pike,  in  which,  though 

Fig.  51. 


Fig.  50.— Brain  of  Perch,  upper  surface.  ''Owen  after  Cuvier.)  a,  Cerebellum ; 
b,  optic  lobes ;  c,  cerebral  lobes  ;  i,  olfactory  ganglia ;  g,  medulla  ;  }),  n,  r,  s,  t,  cra- 
nial nerves. 

Fig.  51.— Brain  of  Perch,  under  surface.  (Owen  after  Cuvier.)  a,  Medulla ;  e. 
hypoaria  ;  /,  pituitary  body  ;  n,  optic  nerves,  decussating  ;  c,  cerebral  lobes  ;  i,  olfac- 
tory ganglia ;  p,  q,  r,  s,  t,  cranial  nerves. 


small,  the  eyes  are  at  the  surface.  In  the  great  majority 
of  Fishes,  however,  these  organs  are  large  and  attain  a 
remarkable  development. 

The  optic  lobes  are  usually  the  largest  divisions  of  the 
brain  in  osseous  fishes,  as  in  the  Perch  (fig.  50),  and 
they  are  commonly  united  by  one  or  more  transverse  com- 
missures. Each  of  them  generally  contains  a  distinct 
cavity  or  '  ventricle,'  and  they  often  bear  on  their  under 
surface    two    smaller   ganglionic   projections,    known    as 


Chap.  VIII.] 


AND    OF    AMPHIBIA. 


117 


*  hypoaria.'  These  bodies  are  well  developed  in  the 
Perch,  and  in  the  Cod  (figs.  51,  57).  Their  use  is  un- 
known, and  it  is  remarkable  that  they  are  structures 
peculiar  to  the  brain  of  Fishes. 

In  connection  with  the  optic  lobes  there  are  also  two 
peculiar  structures,  one  above  and  the  other  below,  known 
as  the  '  Pineal '  and  '  Pituitary '  Bodies  (figs.  53,  3;  60,  3,  e ). 

In   front   of    the    optic   lobes   are    the    already   men- 


FiG.  52. 


Fig.  53. 


Fig.  52.— Brain  of  Carp.  (Ferrier.)  a,  Cerebral  lobes  ;  b,  optic  lobes  ;  c,  cerebel- 
lum and  medulla. 

Fig.  53.— Upper  aspect  of  the  Brain  of  a  Ray,  or  S-kate  (Raia  bati.t).  1,  Olfactory- 
lobes;  2,  the  conjoined  cerebral  lobes;  3,  the  pineal  gland  ;  4,  optic  lobes;  5,  cere- 
bellum ;  6,  medulla,  with  ganglionic  projections.     (Mivart.) 

tioned  Cerebral  Lobes.  They,  like  the  cerebellum,  have 
no  obvious  connection  with  nerves,  and  vary  much  in 
size  in  different  Fishes,  though  they  are  mostly,  as  in  the 
Carp  (fig.  52)  and  the  Perch  (fig.  50),  smaller  than  the 
optic  lobes. 

The  Cerebral  Lobes  are  smallest  in  the  Lamprey  and 
its  allies,  in  the  Herring,  and  in  the  Cod ;  while  they  are 
most  developed  in  the  Skate,  the  Shark,  Polypterus, 
and  Lepidosiren.      In  the  Skate  (fig.  53),   they  coalesce 


118 


THE    BRAIN    OF    FISHES 


into  a  somewhat  flattened,  transversely  elongated  mass, 
showing  only  slight  indications  of  a  median  fissure.  In 
the  Shark  (fig.  48)  they  also  unite  to  form  a  large  almost 
globular  mass  with  little  trace  of  a  median  furrow.  A 
similar  fasion  of  the  two  lobes  occurs  in  some  other  Fishes, 
though  in  the  majority  they  exist  as  spheroids  united  only 
by  a  transverse  commissure.  In  Lepidosiren  the  cerebral 
hemispheres  are  larger  than  all  the  rest  of  the  brain ; 
each  of  them  also  contains  a  cavity  or  ventricle,  which  is 


Fig.  54. 


Fig.  55. 


Fig.  54.— Brain  of  Lepidostcus  or  Gar-Pike.  (Owen.)  7i,  Olfactory  ganglia;  p. 
cerebral  lobes  ;  o,  optic  lobes ;  c,  cerebellum  ;  h,  mednlla ;  /,  fourth  ventricle ;  U, 
lower  boundary  of  medulla. 

Fig.  5,5.— Brain  of  the  Whiting.  (Solly.)  a.  Olfactory  ganglia ;  b,  cerebral  lobes; 
c,  optic  lobes ;  e,  cerebellum  and  medulla. 


prolonged  into  the  olfactory  lobe.     In  these  respects  they 
closely  agree  with  the  cerebral  lobes  of  Reptiles. 

In  the  Gar-Pike  (fig.  54),  the  Perch,  the  Mackerel,  and 
many  other  Fishes,  two  additional  ganglia  known  as  the 
Olfactory  Lobes  lie  immediately  in  front  of  the  cerebral 
lobes,  and  each  of  them  receives  a  long  olfactory  nerve.  * 

■^  The  Lancelot  lias  a  single  olfactory  sac  and  a  single  nerve;  in 
all  otlier  fishes,  except  in  the  Lamprey  and  its  allies,  there  are  two 
nerves  (see  iluxley,  "  Journ.  of  Linn.  Soc."  (Zool.),  vol.  xii.  p.  224). 


Cbap.  VIII.]  AT^D    OF    AMPHIBIA.  119 

But  in  such  Fishes  as  the  Whiting  (fig.  65),  the  Carp 
(fig.  52),  the  Skute  (fig.  53),  the  Shark  (fig.  48),  and 
others,  the  olfactory  gangh'a  are  situated  at  a  distance  from 
the  cerebral  lobes,  with  which  they  are  connected  only  by 
means  of  two  long  and  narrow  outgrowths  or  peduncles. 
In  these  latter  Fish  the  ganglia  are  to  be  found  close  to 
the  olfactory  organs,  from  which  they  receive  numerous 
short  nerves. 

Such  are  the  essential  parts  in  the  brain  of  the  Fish. 
Their  relative  size  or  development  is,  however,  subject  to 
almost  countless  diversities  in  different  genera. 

From  the  foregoing  description,  it  will  be  seen  that 
on3  of  the  principal  characteristics  of  the  Brain  of  Fishes 
is  to  be  found  in  the  serial  arrangement  of  its  parts,  in  a 
line  with  one  another  and  with  the  spinal  cord ;  whilst 
another  is  the  small  mass  of  the  Brain  as  compared  with 
that  of  the  Spinal  Cord,  and  still  more  in  comparison 
with  the  mass  and  weight  of  the  entire  body. 

In  the  former  respect,  at  least,  the  Brain  of  Amphibia 
(fig.  56)  agrees  closely  with  that  of  Fishes.     The  principal 


Fig.  56. — Brain  and  Spinal  Cord  of  the  Frog    a,  Olfactory  lobe.s  ;  b,  cerebral  lobes; 
B,  pineal  body ;  c  and  d,  optic  lobes  ;  e,  cerebellum  ;  h,  spinal  cord. 

divisions  of  the  brain  also  in  these  animals  are  identically 
the  same.  The  Brain  of  the  Frog  is  notable  principally 
for  the  smaller  size  of  its  Cerebellum,  and  also  for  the 
diminished  bulk  of  its  Optic  Lobes  and  Olfactory  Ganglia. 
The  Cerebral  Lobes,  are,  therefore,  proportionately  large. 
The  Spinal  Cord  is  shorter  than  usual,  and  does  not 
occupy  the  whole  length  of  the  '  spinal  canal.' 


120  THE    BRAIN    OF    FISHES 

Tbougli  the  Cerebellum  itself  does  not  appear  to  be 
immediately  connected  with  any  nerves,  the  Medulla 
Oblongata,  from  which  this  part  is  an  outgrowth,  is 
remarkable  in  Fishes,  as  well  as  in  other  vertebrates,  for 
the  number  and  importance  of  the  nerves  with  which  it  is 
connected.  Indeed,  if  the  limits  of  the  Medulla  are 
taken  to  be  those  originally  defined  by  Willis  and  most 
anatomists  anterior  to  Haller  (1762),  they  will  include  the 
*  crura  cerebri ' ;  and  in  that  case  all  the  Cranial  Nerves 
(that  is,  the  nerves  which  pass  inwards  or  outwards 
through  holes  in  the  cranium),  except  the  olfactory  and 
the  optic,  would  have  to  be  described  as  in  direct  con- 
nection with  the  medulla  oblongata. 

The  Cranial  Nerves  of  Fishes  and  of  Amphibia  are, 
with  few  exceptions,  similar  in  number  and  nature  to  those 
existing  throughout  the  vertebrate  series,  so  that  they  may 
with  advantage  be  here  enumerated.  According  to  the 
classification  of  Willis  (1664),  which  is  generally  followed, 
they  are  said  to  consist  of  nine  pairs,  counting  from  before 
backwards.     {See  figs.  46,  57,  58.) 

1st  Pair.     Olfactory, 

2nd     „        Oj:)tlc. 

3rd     „        Motor  oculi  communis;  supplying  all  but  two  of 

the  muscles  of  the  eyeball  and  the  circular 

fibres  of  the  iris. 
4'th     „        Troclilearis ;  supplying  the  superior  oblique  muscle 

of  the  eye. 

^Large  root :  the  nerve  of  general  sen- 
sibility for  the  side  of  the  head, 
,.,,  .  face,  &c. 

oth     „        Trtgemmus^,  ^^^^^^   ^^^^  ^  supplying   muscles   con- 

nected   with  the  jaw  (muscles  of 

mastication). 
6th     ,5        Motor    oculi    externus ;     supplying    the    external 
k  rectus  muscle  of  the  eyeball. 


Cjiap.  VIII.]  AND    OF    AMPHIBIA.  121 

( 


Auditory. 

^'^     »»     ■  Facial;  supplying  the  superficial  muscles  of  the 
face,  &c. 
fGlosso-'pharyngeal  (gustatory  nerve  and  nerve  of 

common  sensibility  for  the  pharynx). 
Vagus,  or  Pneumo gastric  (sensory  nerve  of  respi- 
8th     „      ^  ratory    organs,   heart,  alimentary  canal,  liver, 

kidneys,  &c. 
8_pinal  accessory;    supplying  the  muscles  of  the 
larynx,  &c. 

9th      ,       Sublingual,  or  Hypoglossal ;  motor  nerve  of  tongue 
and  of  muscles  which  move  it. 


From  this  table  it  will  be  seen  that  three  of  the  '  pairs  ' 
of  cranial  nerves  (5th,  7th,  and  8th)  are  compound  in  their 
nature.  Their  parts  have,  moreover,  little  in  common, 
except  for  the  fact  that  the  components  of  each  so-called 
*  pair  '  in  man  and  many  of  the  lower  animals  pass  side  by 
side  through  the  same  hole  in  the  skull.  This,  indeed, 
seems  to  have  been  the  principal  reason  actuating  the 
earlier  anatomists  when  they  grouped  them  together.* 
No  cranial  nerves  answering  to  the  9th  pair  exist  in 
Fishes :  their  functions  being  discharged  by  branches 
from  the  first  spinal  nerve.  The  motor  root  of  the  8th, 
the  '  spinal  accessory,'  is  also  less  distinct  as  a  separate 
nerve  in  Fishes  and  some  Eeptiles,  than  it  is  in  higher 
vertebrates. 

Looked  at  from  the  point  of  view  of  the  functions  which 

*  Except  in  the  case  of  the  two  divisions  of  the  5th  nerve,  this 
grouping  was  not  respected  in  the  classification  of  Soemmering 
(1778).  According  to  him,  the  cranial  nerves  were  to  be  regarded  as 
twelve  pairs,  the  first  six  agreeing  with  those  of  WilHs,  whilst  the 
facial  is  called  the  7th,  the  auditory  the  8th,  the  glosso-pharyngeal 
the  9th,  the  vagus  the  10th,  the  spinal  accessory  the  11th,  and  the 
sublingual  the  12th. 


122 


THE    BRAIN    OF    FISHES 


I.  Nerves  of 
Special  Sense. 

II.  Nei-ves  of 
General  Sensihility. 


III.  Motor  Nerves. 


they  subserve,  these  Cranial  Nerves  fall  into  the  following 
groups  : 

(  Olfactory. 
J  Optic 
I  Auditory. 

Gustatory. 

Large  root  of  5th. 

Part  of  Glossopharyngeal. 

Vagus  (the  visceral  nerve). 
C  Motores    oculi  (8rd,  4th,  and  6th 

pairs). 
I   Small  root  of  5th. 
j  Facial  nerve. 

Spinal  accessory. 
\^  SubHngual  or  Hypoglossal. 

Taking  the  larger  view  held  by  Willis  and  others,  as  to 
the  limits  of  the  Medulla  Oblongata,  and  including  under 
this  name  all  those  parts  of  the  Brain, 
with  the  exception  of  the  cerebellum, 
posterior  to  the  optic  lobes,  we  find 
the  several  pairs  of  true  cranial  nerves 
(from  3rd  to  9th  inclusive)  attached  to  it 
on  each  side,  and  for  the  most  part  in 
the  order  of  their  numeration  (the  3rd 
issuing  from  it  close  to  the  optic  lobes, 
and  the  9th  close  to  the  junction  of  the 
medulla  with  the  spinal  cord),  with  the 
reservation  that  in  Fishes  the  nerves  of 
the  8tli  pair  are  the  last  which  pertain 
to  the  medulla. 

The  '  sensory  '  nerves  attached  to  the 
Medulla,   are,  like  those  of  the  spinal 
cord  marked  by  ganglionic  swellings 
near  or  at  the  points  of  attachment  of 
such  nerves  (p.  44). 

Thus  the  roots  of  the  Vagus  or  Pneumogastric  in  a  large 


Fig.  57.— Brain  of  the 
Cod,  under  surface. 
(Owen.)  p, Cerebral  lobes  ; 
o,  optic  lobes  ;  «,  hypoa- 
ria  ;  p,  pituitary  body  ; 
a,    anterior    pyramids ; 

2,  optic  nerves,  crossing  ; 

3,  ocido-niocor ;  5,  trij^^e- 
niinns  ;  0,  external  ocu- 
lar ;  7,  auditory  ;  8,  vaj^us 
and  glosso-iiharyngeal. 


Chap.  VIIL]  AND    OF    AMPHIBIA.  123 

number  of  fishes  become  swollen  into  distinct  ganglia  at 
their  point  of  junction  with  the  Medulla,  and  in  some — • 
such  as  the  Carp,  the  Torpedo,  the  Electric  Eel,  and  the 
Skate — these  lateral  ganglia,  situated  at  the  side  of  the 
cerebellum,  are  exceptionally  large.  The  Glosso-pharyn- 
geal  is  in  reality  only  a  large  separate  branch  of  the 
vagus.  In  some  fishes  it  joins  one  of  the  roots  of  the 
vagus ;  and,  even  where  this  external  junction  does  not 
exist,  an  internal  union  is  effected  by  the  smaller  nerve 
entering  the  nucleus  of  the  larger  one. 

A  little  anterior  to  the  ganglia  of  the  Vagi,  large 
swellings  are  also  frequently  met  with  in  connection  with 
the  roots  of  the  Trigeminal  nerves  (fig.  10),  which  in 
fishes  are  mostly  very  large,  and  have  an  extensive  dis- 
tribution even  beyond  the  region  of  the  head.  The 
remaining  sensory  nerves  of  the  medulla — the  Auditory — 
are  attached  to  it  by  tw^o  or  three  roots,  between  the  vagi 
and  the  5th  nerves.  These  nerves  are  large,  though  it 
is  only  rarely  that  a  distinct  ganglionic  swelling  is  found 
at  their  point  of  junction  with  the  medulla  (fig.  11).  The 
ganglia  are  usually  embedded  in  the  Medulla  itself,  and 
some  of  its  roots  soon  join  another  large  ganglion : 
viz.,  the  Cerebellum.  This  apparent  connection  of  the 
auditory  nerves  with  the  great  motor  ganglion  in  Verte- 
brates, whatever  its  explanation  may  be,  is  quite  in  har- 
mony with  the  close  relation  of  the  *  auditory  saccules  ' 
and  nerves  to  the  pedal  ganglia  in  Mollusks,  and  with 
their  relation  to  the  most  active  motorial  centres  of  the 
ventral  cord  in  those  Insects  (such  as  Locusts  and  Grass- 
hoppers) in  which  the  so-called  *  auditory  saccules  '  have 
been  positively  detected.* 

*  The  Organs  of  Hearing  in  Fishes  are  always  double,  as  in 
invertebrate  animals.  They  are,  moreover,  situated  within  the 
body,  and  mostly  have  no  connection  with  its  surface.     Sometimea 


124      THE    BRAIN    OF    FISHES    AND    OF    AMPHIBIA. 

The  ganglia  at  the  roots  of  the  Olfacton^  and  Optic 
nerves  are  sufficiently  obvious  and  remarkable,  so  that 
no  further  reference  need  here  be  made  to  them,  except 
to  point  out  that  they,  together  v^^ith  the  ganglia  at  the 
roots  of  the  Trigeminus  and  Vagus,  undergo  a  propor- 
tionate diminution  in  size  as  the  Cerebral  Lobes  become 
better  developed,  among  Eeptiles  and  Birds — changes 
which  seem  to  imply  that  functions  previously  discharged 
by  lower  sensory  ganglia  are  gradually  passed  on  and 
merged  as  products  of  a  higher  order  of  cerebral  activity, 
when  such  higher  co-ordinating  centres  arise  and  come 
into  fuller  action. 

The  ganglia  at  the  roots  of  the  Auditory  nerves,  how- 
ever, do  not  seem  to  attain  their  maximum  size  till  we 
come  to  Eeptiles,  a  fact  which  may  be  accounted  for  by 
the  probably  rudimentary  state  of  this  sense  endowment 
among  Fishes. 

It  will  be  found,  therefore,  to  be  a  peculiarity  of  all 
Sensory  Nerves  in  vertebrate  animals  that  their  fibres  pass 
through  such  Ganglia  before  they  impinge  upon  the  great 
nerve  centres — a  fact  originally  noticed  by  Sir  Charles 
Bell.  No  corresponding  ganglia  exist  in  connection  with 
motor  nerves,  outside  the  anterior  cornua  of  the  spinal  cord. 

they  are  lodged  outside  the  cranial  cavity,  sometimes  in  the  walls 
of  the  cranium,  and  sometimes  half  within  and  halt  outside  this 
cavity.  Their  structure  is  extremely  simple,  and  in  some  fishes 
they  are  only  a  very  little  more  complex  than  the  'auditory 
saccules '  met  with  in  the  Cuttle-fish.  In  the  fact  that  in 
Fishes,  as  in  other  vertebrates,  the  auditory  organs  are  always 
situated  in  the  head,  we  have  a  departure  from  the  rule  so  commonly 
obtaining  among  Invertebrates.  Perhaps,  in  its  simplest  forms, 
this  apparatus  may  have  as  much  to  do  with  the  organism's  Space 
relations  as  with  Hearing  (see  p.  218). 


CHAPTER  IX. 

THE   BRAIN    OF    REPTILES    AND   OF   BIRDS. 

The  nervous  system  of  Reptiles  generally  exists  in  a 
slightly  more  developed  form  than  that  which  is  common 
amongst  Fishes. 

The  Spinal  Cord  occupies  the  whole  length  of  the 
spinal  canal.  It  is  slender  and  almost  uniform  in  thick- 
ness in  Serpents,  though  it  is  relatively  stouter  in  Croco- 
diles and  their  allies.  In  the  latter  it  also  presents 
decided  swellings  in  those  regions  whence  the  nerves  are 
given  off,  on  each  side,  for  the  fore  and  hind  limbs. 

The  principal  divisions  of  the  Brain  are  the  same  in  all 
kinds  of  Reptiles,  though,  as  might  have  been  expected  from 
the  varied  form  and  nature  of  the  different  representatives 
of  this  great  class,  the  respective  development  of  the 
several  divisions  of  the  organ  varies  much  in  different 
orders. 

The  Medulla  Oblongata,  directly  continuous  with  the 
spinal  cord,  slightly  widens  at  its  upper  part,  where  it  is 
surmounted  by  the  Cerebellum.  This  latter  structure,  in 
the  Lizard  (fig.  59)  and  its  allies,  is  very  small,  consisting 
only  of  a  thin  lamella.  The  cerebellum  is  larger,  how- 
ever, among  Serpents  (fig.  58),  and  it  becomes  still  more 
developed  in  Turtles  (fig.  61)  and  Crocodiles. 

The  Optic  Lobes  are  relatively  smaller  in  most  Reptiles 
than  they  are  among  Fishes  ;  and  in  the  Boa  Constrictor 


126  THE    BRAIN    OF    REPTILES 

they  show  a  transverse  fissure  which  divides  the  two  bodies 
into  four  parts,  corresponding  to  the  '  corpora  quadrigemina' 


Fin.  /JR.  -Brain  and  Cranial  Norvc=»  of  ]3oa  Constrictor.  (Rymcr  Jones,  after  Swan.) 
«,  Cereljral  lobes  ;  b,  ojitic  lobes  with  transverse  depression  ;  c,  cerebellum  ;  d,  mem- 
brane of  the  nose  ;  1,  olfactory  norve  ;  2,  optic  nerve  ;  3,  third,  or  common  oculo- 
muscular  nerve  ;  4,  fourth,  or  trochlear  nerve  to  the  superior  oblique  muscle  of  the 
eye  ;  5,  first  tnink  of  the  fifth  ;  6,  se  ond  trunk  of  the  fifth  ;  7,  third  trunk  of  the 
fifth  ;  S,  hard  portion  of  the  seventh  nerve  ;  9,  auditory  nerve  ;  10,  glosso-pharyngeal 
nerve  ;  11,  trunk  of  the  vagus  nerve;  VI,  nintli  nerve.  Tlic  last  three  nerves  are 
intimately  connected  with  one  another,  and  with  13,  a  sympathetic  ganglion 


Chap.  IX.] 


AND    OF    BIRDS. 


127 


of  higher  Yertehrates  (fig.  58,  h).  Between  the  optic 
lobes  and  the  next  great  division  of  the  brain,  the 
cerebral  lobes,  we  find  the  so-called  '  pineal  body '  (fig. 
61,  j),  projecting  upwards,  and  in  a  more  developed  form 
than  that  which  is  met  with  in  Fishes.  The  nature  and 
uses  of  this  body  are  wholly  unknown.  It  is  chiefly 
notorious  from  the  fact  that  Descartes  pointed  to  the 
corresponding  structure  in  the  human  brain  as  the  "  seat 
of  the  Soul." 

The  Cerebral  Lobes  in  the  Lizard  (fig.  59)  and  its  allies, 
as  well  as  in  Amphibia,  are,  in  comparison  with  other 
parts  of  the  brain,  much  larger  than  in 
Fishes.  This  is  due  only  in  part  to  an 
absolute  increase  in  their  development,  as 
there  seems  to  be  some  diminution  in  the 
size  of  the  olfactory  and  optic  lobes  and  the 
cerebellum.  In  Serpents,  Crocodiles,  Tur- 
tles (fig.  61),  and  their  allies,  however,  we 
meet  with  a  decided  absolute  increase  in  the 
size  of  the  cerebral  lobes.  In  Crocodiles, 
for  instance,  they  are  much  larger  and 
broader  than  other  parts  of  the  brain, 
though  their  surface  is  still  quite  smooth. 
Each  lobe  contains  a  cavity  or  '  ventricle  ' 
in  its  interior,  as  in  some  of  the  higher 
Fishes.  But  in  Reptiles  the  i^entricle  is 
larger,  and,  projecting  from  its  anterior 
and  inner  surface  there  is  a  rounded  emi- 
nence, supposed  by  some  anatomists  to  represent  a  body  of 
considerable  importance — which  is  known  amongst  higher 
vertebrates  as  the  '  Corpus  Striatum '  or  striate  body. 

Each  Cerebral  Lobe  is  connected  with  its  corresponding 
optic  lobe  and  with  the  same  half  of  the  medulla  oblongata, 
by  means  of  a  thick  and  composite  prolongation  called  the 


Fig.  59.— Brain  of 
Lizard  (Lacerta  viri- 
dis).  a,  Cerebral 
hemispheres  ;  b,  op- 
tic lobes ;  c,  cerebel- 
lum ;  d,  spinal  cord  ; 
e,  fourth  ventricle  ; 
/,  ijineal  body ;  g, 
olfactory  ganglia. 
(Owen.) 


128  THE    BRAIN    OF    REPTILES 

*  cerebral  peduncle.'  On  the  upper  and  inner  part  of  each 
of  these  composite  peduncles,  just  anterior  to  the  optic 
lobes,  there  is  a  small  projection,  supposed  to  answer  to 
another  very  important  ganglionic  body,  which,  in  higher 
vertebrates,  is  known  as  the  '  Thalamus.'  As  to  the 
identity  of  these  bodies,  however,  some  difference  of 
opinion  exists.  They,  together  with  the  inner  faces  of 
the  peduncles  on  which  they  are  situated,  constitute  the 
lateral  boundaries  of  another  brain  cavity,  known  as  the 
'  third  ventricle,'  which  is  mostly  covered  over  above,  by 
the  backward  extension  of  the  cerebral  lobes. 

A  band  of  fibres,  termed  the  '  anterior  commissure,' 
which  connects  certain  regions  of  the  two  cerebral  lobes — 
hereafter  to  be   specified — arches  across  the  anterior  part 


Fig.  60.— Vertical  Longitudinal  Section  of  the  Brain  of  Perch.  (Mivart.)  1,  Olfac- 
tory lobe  ;  2,  cerebral  lobe  ;  3,  pineal  body ;  4,  optic  lobe,  with  large  cavity  within ; 
6,  cerebellum  ;  6,  pituitary  body  ;  7,  hypoarium. 

of  this  Third  Ventricle ;  whilst  the  upper  strata  of  the  two 
cerebral  peduncles  are  connected  by  means   of  a  smaller 

*  posterior  commissure,'  crossing  the  posterior  boundary  of 
this  ventricle,  just  in  front  of  the  optic  lobes.  The 
peduncles  or  attachments  o^f  the  before-mentioned  '  pineal 
body'  rre  structural  relation  with  the  posterior  com- 
missure. 

The  Third  Ventricle  is  continuous  below  with  a  funnel- 
like prolongation,  at  the  extremity  of  which  is  a  structure 
named   tlie    'pituitary   body,'   not   altogether   unlike   the 

*  pineal  body,'  and  whose  use  is  simibirly  unknown. 
Though  present  in  Fishes  and  higher  Vertebrata,  the 
pituitary  body  is  especially  large  in  many  Eeptiles. 


CflAP.    IX.] 


AND    OF    BIRDS. 


129 


The  Olfactory  Lobes  have,  throughout  the  class  of 
Reptiles,  a  smaller  proportionate  size  than  in  Fishes.  In 
Serpents  (fig.  58)  and  Crocodiles  they 
are  situated,  as  in  some  of  the  last-named 
creatures,  at  a  distance  from  the  cerebral 
lobes — being  connected  with  them  by 
long  peduncles.  In  Lizards  and  their 
allies  the  olfactory  lobes  are  more  or 
less  continuous  with  the  cerebral  lobes 
(fig.  59)  ;  while  in  the  Turtle  and  other 
Chelonians,  they  are  marked  off  from 
the  anterior  extremities  of  the  cerebral 
hemispheres  only  by  a  slight  constriction 
(fig.  61,  a),  and  each  olfactory  lobe  is 
penetrated  by  a  prolongation  from  the 
corresponding  cerebral  '  ventricle.' 

With  regard  to  the  Cranial  Nerves 
of  Reptiles,  it  may  be  remarked  that  the 
Trigeminus  and  the  Vagus  (or  visceral 
nerve)  are  still  very  large,  but  neither  of 
them  swell  at  their  roots  into  such  dis- 
tinct ganglia  as  in  Fishes.  The  Glosso- 
pharyngeal, or  nerve  of  taste,  joins  the 
internal  nucleus  of  the  Vagus  in  Amphi- 
bia, though  in  Serpents  and  higher  Rep- 
tiles it  has  a  nucleus  of  its  own,  distinct 
from  that  of  the  latter.  The  Auditory 
nerves  are  lar^e,  and  in  Turtles,  Croco-      ^,     .,     „   .    _ 

^    '  ,  '  Fig.  61.- Brain  of  Tur- 

diles,  and  their  allies,  they  swell  into  tie,  side  view.  (Soiiy.) 
distinct  ganglionic  enlargements  at  the  ^^e^wLrXe! 
back  of  the  medulla,  on  each  side  of  the  c,  optic  ganglion  ;  e,  te- 

n  n    J.1        ,  p         i.1  j^    •    1      »  rebellum  ;  g,  ganglion  at 

lloor  Ol     the      lOUrth  ventricle.  root  of  vagus  nerve;  J, 

The   brain  of   Reptiles,  like   that    of  pi^^e^i^^dy- 
Fishes,    is  still   characterized  by  the  arrangement  of  its 


130  TQE    BRATN    OF    REPTILES 

several  parts  and  the  spinal  cord  in  the  same  horizontal 
plane,  and  by  the  small  size  of  the  Brain  as  compared  with 
the  latter  structure.  Still,  the  brain  is  more  nearly  equal 
in  weight  to  the  cord  than  it  is  in  Fishes,  and  it  also 
bears,  in  the  majority  of  Eeptiles,  a  greater  proportion  to 
the  total  body-weight. 

But  in  Birds  we  find  the  Brain  attaining  a  notably 
greater  size  in  proportion  to  the  bulk  of  the  Spinal  Cord 
than  it  has  among  Reptiles,  and  also  presenting  other 
signs  of  increased  development. 

According  to  Leuret,  the  average  proportional  weight  of 
the  brain  to  the  body  in  the  four  undermentioned  classes, 
as  deduced  from  numerous  observations  on  different 
representatives  of  each,  may  be  stated  to  be  as  follows  : 

In  FiSTii:s as  1  to  5,668      In  Birds as  1  to  212 

In  Eki'Tiles as  1  to  1,321       In  Mammalia...  as  1  to  186 

These  figures  must,  of  course,  be  regarded  merely  as 
aj)proximate  averages. 

No  peculiarity  worthy  of  note  exists  in  the  Spinal  Cord 
of  Birds,  except  that  in  the  situation  of  its  posterior 
enlargement,  corresponding  with  the  attachment  of  the 
great  nerves  of  the  legs,  the  posterior  columns  of  the 
cord  diverge  from  one  another,  and  shortly  again  approxi- 
mate so  as  to  form  a  space,  known  as  the  '  rhomboidal 
sinus.'  This,  however,  is  an  anatomical  peculiarity  to 
which  no  physiological  significance  is  attached. 

The  Medulla  Oblongata,  from  the  back  of  which  the 
cerebellum  is  developed,  is,  in  lairds,  decidedly  broader 
than  the  spinal  cord.  As  in  lower  vertebrates,  the  diver- 
gence of  the  upper  or  posterior  columns  of  the  cord 
leaves  at  the  corresponding  surface  of  the  medulla  the 
space  known  as  the  '  fourth  ventricle,'  which  becomes  much 


Chap.  IX.] 


AND    OF    BIRDS. 


131 


more  completely  roofed  over  than  it  is  in  Fishes  or  Rep- 
tiles, by  the  under  surface  of  the  now  larger  cerebellum 
(fig.  64).  The  Auditory  nerves  arise  from  about  the  middle 
of  the  floor  of  the  fourth  ventricle,  where,  as  in  some 
Reptiles,  they  are  connected  with  a  distinct  ganglionic  emi- 
nence on  each  side  of  the  middle  line.  The  Trigeminus 
is  always  large,  and  exceeds  all  the  other  cranial  nerves  in 
size,  with  the  exception  of  the  Optic. 

The  Cerebellum  is  much  larger  than  we  have  hitherto 
met  with  it — with  the   single   exception  of   that  of    the 


Fig.  62. 


Fig. 


Fig.  64. 


Fig.  62.  — Bi-nin  of  Pigeon.  (Ferrier.)  a,  Cerebral  hemispheres  ;  b,  optic  lobe ; 
C,  cerebellum  with  transverse  furrows  and  very  small  lateral  lobes. 

Fig.  63. — Brain  and  part  of  Spinal  Cord  of  Chick  16  days  old,  showing  the  optic 
lobes  (/>)  still  in  contact — at  their  inner  borders.     (Owen,  after  Anderson.) 

Fig.  64.— Biain  and  part  of  Spinal  Cord  of  Chick,  20  days  old,  showing  the  optic 
lobes  (6)  now  widely  scimrated,  and  cerebellum  (c)  greatly  developed.  (Owen, 
after  Anderson.) 


Shark.  It  now  consists  of  a  more  or  less  ovoid  median 
lobe  (deeply  scored  by  transverse  furrows),  and  of  two 
much  smaller  lateral  portions,  which  project  slightly  be- 
hind the  optic  lobes  (fig.  62,  c). 

These  Optic  Lobes  are  pushed  aside  and  depressed  so 
that  they  are  partly  covered  by  the  large  cerebral  hemi- 
spheres (figs.  63,  64).  In  form  they  are  rounded  bodies, 
showing  no  trace  of  a  transverse  division.  Each  contains 
a  cavity,  opening  below  and  internally  into  a  subjacent 
passage  or  canal,  which  serves  to  connect  the  fourth  with 


132  THE    BRAIN    OF    REPTILES 

the  third  ventricle.  The  two  optic  lobes  are  connected 
with  one  another  by  a  wide  commissure,  which  constitutes 
the  roof  of  the  above-mentioned  passage.  The  optic 
nerves  arise  from  the  under  surface  of  these  lobes. 
They  are  lamellated  structures ;  and  at  the  place  where 
the  two  nerves  cross  one  another,  their  lamellae  interlock ; 
instead  of  the  one  nerve,  as  a  whole,  passing  over  the 
other,  as  is  the  case  in  Fishes. 

In  front  of  the  optic  lobes  are  the  cerebral  peduncles  or 

*  Crura  Cerebri/  between  which  the  *  third  ventricle  '  is 
situated.  Stretching  across  this  space,  immediately  in 
front  of  the  optic  lobes,  is  the  '  posterior  commissure '  of 
the  brain,  with  wdiich  (as  in  Reptiles)  the  peduncles  of 
the  '  pineal  body  '  are  connected — a  structure  sometimes 
seen  to  project  in  the  brain  of  Birds  between  the  cerebral 
hemispheres  and  the  cerebellum.     A  little  in  front  of  this 

*  posterior  commissure  '  a  rounded  prominence  may  be 
seen  on  the  upper  and  inner  aspect  of  each  cerebral 
peduncle — that  is,  on  the  portion  which  constitutes  part 
of  the  lateral  boundary  of  the  third  ventricle.  A  similar 
projection  has  been  previously  alluded  to  as  occurring 
in  some  Reptiles,  and  it  is  supposed  to  correspond 
with  the  important  structures  termed  the  ^Thalamus' 
of  a  Mammal's  brain.  The  anterior  part  of  the  floor  of 
the  third  ventricle  still  communicates,  by  a  short  hollow 
peduncle,  with  the  peculiar  '  pituitary  body  '■ — a  structure 
which,  in  Birds#(tig.  Gf),  g)  is  proportionately  less  de- 
veloped than  in  Reptiles  and  Fishes  (fig.  *30,  g). 

The  Cerebral  Lobes  are  large  and  more  or  less  rounded, 
though  they  are  flattened  at  their  inner  faces,  where  tney 
come  into  contact  with  one  another  (fig.  65).  These  all- 
important  divisions  of  the  brain  are  smooth  and  still 
devoid  of  convolutions;  yet  in  some  birds  thei'e  are  traces 
of  a  depression,  answering  to  a  well-marked  fissure  (the 


CuAP.  IX.]  AND    or    BIRDS  133 

*  sylvian ')  always  recognizable  in  the  brain  of  higher 
Mammals.  The  cavity  within  each  of  the  cerebral  lobes — 
answering  to  the  '  lateral  ventricles  '  of  the  human  brain* 
— is  comparatively  large,  and  projecting  from  the  anterior 
and  external  part  of  the  floor  of  each  of  them,  there  is 
an  eminence  generally  admitted  to  correspond  to  the 
'  Corpus  Striatum '  in  the  brain  of  Man  and  Mammals 
generally.  The  inner  walls  of  ^le  lateral  ventricles  are 
thin,  and  almost  in  contact  with  one  another.  They  con- 
stitute the  inner  boundaries  of  the  cerebral  lobes. 

Fig.  66. 


e 

Fig.  65.— Brain  of  Common  Fowl  in  udult  condition.  (Spurzheim.)  c,  Optic  lobea 
in  part  hidden  by  (6)  cere  oral  hemispheres. 

Fig.  %'6. — Brain  of  Pigeon,  side  view.  (Mivart.)  1,  Olfactory  lobe ;  2,  cerebral 
hemisphere  ;  3,  pineal  body  ;  4,  optic  lobe  ;  5,  cerebellum  ;  6,  pituitary  body  ;  8,  optic 
nerve. 

These  lobes  are  structurally  connected,  as  in  Eeptiles 
and  Fishes,  by  a  well-marked  '  anterior  commissure,' 
while  above  and  behind  it  there  exists  another  set  of  con- 
necting fibres,  deemed  by  some  anatomists  to  represent 
the  commencement  of  the  ^  Corpus  Callosum.'  This  latter 
is  the  great  transverse  commissure  which  unites  the  two 
halves  of  the  brain,  and  whose  size  increases  as  we  pass 
from  lower  to  higher  orders  of  the  Mammalian  series. 

^  These  are  the  lirst  and  second  ventricles.  The  third  is 
situated  between  the  cerebral  peduncles,  the  fourth  at  the  back 
of  the  medulla,  and  the  fifth  ventricle  will  be  subsequently  re- 
ierred  to  in  the  description  of  the  brain  of  Quadrupeds. 

7 


134  THE    BRAIN    OF    REPTILES 

The  Olfactory  Lobes,  comparatively  small  in  size,  are 
found  in  front  of,  and  j)artly  beneath,  the  cerebral  lobes 
(fig.  66,  i).  They  are  true  outgrowths  from  the  cerebral 
lobes,  and  the  cavity  within  each  of  them  is  continuous 
through  its  peduncle  with  that  of  the  corresponding 
ventricle.  Each  '  lateral  ventricle  '  is,  in  fact,  prolonged 
into  the  olfactory  ganglion  of  the  same  side. 

Looking  to  the  general  characteristics  of  the   Brain  in 
Birds,  we  find  that  the  Cerebral  Lobes  and  the  Cerebellum 
have  attained  a  much  greater  development  than  is   to  be 
met  with  among  Fishes  and  Rep- 
tiles ;  while  the  relatively  smaller 
Optic  Lobes   are  displaced  down- 
wards   and   outwards,    as    though 
from  the  pushing  forwards  of  the 
cerebellum.     The  several  parts  of 
the  Brain  are  no  longer  in  serial 
order,  and  in  the  same  horizontal 
plane  with  the  Spinal  Cordo     The 
greatly    increased    w^eight    of  the 
Fig.  67.-Brain  of  Sea  G.iii  ^rgau  as  a  wholo,   in  Comparison 

(Owen.atterAnderson.)a,  Cere-    ^Jth    that    of   the    COrd    and    of   the 
bral hemispheres ;  6,opticlobe8;  .  ^ 

c,  cerebellum ;  d,  spinal  cord.       entire  body,  are   also  seen  to  be 
marked  features,  distinguishing  the 
Brain  in  Birds  from  that  of  lower  Vertebrates. 

The  Visceral  Nervous  System  in  Lower  Verte- 
brates.— As  an  addition  to  this  account  of  the  Cerebro- 
spinal Axis  in  Fishes,  Amphibia,  Reptiles,  and  Birds, 
a  word  or  two  may  here  be  appropriately  said  in  regard 
to  the  Visceral  System  of  Nerves  met  with  in  these 
animals. 

We  saw  reason  to  believe  (p.  110)  that  impressions 
emanating  from  the  Viscera  constitute  an  important  part 


Chap.  IX.]  AND    OF    BIRDS.  135 

of  the  general  litock  of  afferent  impressions  which  arouse 
the  brain  activity  and  mental  life,  such  as  it  is,  of  Inver- 
tebrate animals ;  and  that  such  impressions  furnish  the 
internal  promptings  or  stimuli  inciting  these  animals  to 
not  a  few  of  the  acts  and  movements  they  are  accustomed 
to  perform. 

No  excuse,  therefore,  is  needed  for  what  might  at  first 
sight  seem  a  departure  from  our  proper  subject,  in  taking 
account  of  this  visceral  portion  of  the  Nervous  System. 
All  the  avenues  whence  impressions  come  to  the  supreme 
centres,  must,  in  fact,  be  considered  by  any  one  who 
would  properly  understand  the  real  share  of  the  work 
which  the  Brain  takes  as  an  Organ  of  Mind. 

The  Visceral  System  of  Nerves  in  Fishes,  as  in  other 
Vertebrates,  is  divisible  into  two  main  parts,  which,  never- 
theless, are,  to  a  great  extent,  distributed  together  and  to 
the  same  organs.  There  is,  in  the  first  place,  a  set  of 
Cerebral  Systemic  Nerves,  represented  by  the  Glosso- 
pharyngeal and  the  Vagus  or  Pneumogastric — and  these 
seem  to  be  almost  wholly  afferent  nerves  conveying  im- 
pressions from  the  Viscera  to  the  Medulla.  Secondly, 
there  is  the  *  Sympathetic  System '  of  Nerves,  which, 
though  to  a  certain  extent  an  independent  system,  is 
also  closely  related  to  the  Cerebro- Spinal  Axis,  by 
means  of  free  intercommunications  passing  between  the 

*  sympathetic '  ganglia,  and  the  anterior  spinal  nerves 
as  well  as  most  of  those  which  are  attached  to  the 
medulla. 

In  this  latter  system  there  are  afferent  and  efferent 
fibres    passing    between    the    Viscera    and    the    several 

*  sympathetic  ganglia  '  with  which  they  are  in  relation ; 
while  these  ganglia  are,  in  their  turn,  connected  by 
afferent  and  efferent  fibres  with  the  cerebro-spinal  axis, 
in  the  manner  above  indicated.     Though  there  may  be, 


136  THE    BKAIN    OF    REPTILES 

and  probably  is,  a  considerable  amount  of  independent 
activity  on  the  part  of  the  '  Sympathetic  System,'  the  action 
of  its  several  parts  is  also  subject  to  the  controlling  and 
regulating  influence  of  certain  cerebro- spinal  centres,  with 
which  they  are  connected  in  the  manner  above  referred  to. 

In  the  Suctorial  Fishes  and  the  Lepidosiren,  the  '  Sym- 
pathetic System '  is  said  not  to  exist,  though  the  Cerebral 
Systemic  Nerves  are  large  and  widely  distributed  over  the 
viscera.  In  the  Sharks  and  Rays,  also,  this  system  is  ill- 
developed,  but  in  the  majority  of  osseous  Fishes  it  consists 
of  a  cord  on  each  side  of  the  spine,  forming  connections 
wilh  the  cerebral  and  spinal  nerves,  and  in  some  of  these 
situations  developing  small  ganglia  and  sending  off 
branches  towards  the  viscera,  which  unite  with  others 
from  the  Yagus  nerve,  so  as  to  form  large  median  'plex- 
uses,' or  '  plexuses  '  and  ganglia,  whence  multitudes  of 
fibres  are  distributed  to  the  different  internal  organs. 
Many  differences  of  detail  occur  in  different  Fishes. 

In  Reptiles,  also,  there  are  various  minor  modifications ; 
but,  on  the  whole,  the  connections  of  the  '  Sympathetic 
System  '  with  spinal  nerves  are  more  developed  in  these 
animals,  and  the  Ganglia  at  such  points  of  junction  are 
more  numerous  and  distinct.  In  Birds  the  distribution 
of  the  Visceral  System  of  Nerves  also,  in  the  main,  tends 
to  approximate  pretty  closely  to  the  general  plan  above 
indicated,  which  will  be  described  in  further  detail  when 
we  come  to  speak  of  its  more  complex  development  among 
higher  Vertebrates. 

By  means,  therefore,  of  this  double  set  of  Visceral 
Nerves,  the  internal  organs  are  brought  into  close  relation 
with  one  another,  as  well  as  with  the  Spinal  Cord  and 
wit-li  the  Brain. 

We  are  not  fairly  entitled  to  measure  the  intensity 
of  the  systemic  impressions  of  a  Fish,  a  Reptile,   or  a 


Chap.  IX.]  AND    OP    BIRDS.  137 

Bird,  by  that  of  tliose  with  which  we  are  ourselves  famihar. 
In  such  aninials  many  visceral  impressions  may  be 
decidedly  attended  by  more  of  conscious  accompaniment 
than  those  which  we  experience,  and  they  may  enter  in  a 
much  larger  proportion  into  the  web  of  sensory  impressions 
constituting  the  basis  of  the  conscious  life  of  such  creatures. 
Professor  Owen  truly  says  of  Fishes  that,  "  the  appetite 
for  food  appears  to  be  their  predominant  desire,  and  pro- 
viding for  its  gratification  to  form  their  chief  occupation." 
Certain  it  is,  that  when  prompted  by  different  visceral 
states,  animals  may  show  an  extraordinary  amount  of 
sensorial  activity  and  power  of  executing  related  muscular 
movements.  The  sensorial  endowments  of  the  Shark, 
of  the  Python,  or  of  the  Vulture,  are,  when  these 
creatures  are  under  the  influence  of  hunger,  exalted  to 
the  highest  degree  ;  so  that  at  such  times  either  of  them 
may  become  keenly  sensitive  to  odours,  sounds  or  sights 
which,  had  they  been  in  a  state  of  satiety,  might  have 
passed  wholly  unheeded.  Similar  difi'erences  also  exist 
between  the  degree  of  sensorial  activity  of  animals 
swayed  by  sexual  desires,  and  those  in  whom  such  feelings 
are  quiescent.  These  two  classes  of  visceral  promptings 
largely  instigate  and  dominate  the  brain  activity  of  all 
lower  animals,  and  when  the  related  needs  or  desires 
no  longer  exist,  and  no  longer  rouse  the  creature's  senso- 
rial activity,  sleep  is  apt  to  come,  as  with  a  veil,  and  sever 
for  a  time  the  correspondence  between  the  organism  and 
the  outer  world. 


CHAPTER  X. 


THE    SCOPE    OF    MIND. 


Much  needless  confasion  is  often  thrown  over  \ihQ 
study  of  mental  phenomena  by  the  mode  in  which  the 
subject  is  regarded,  and  by  the  phraseology  in  common 
use.  It  is  customary  to  speak  of  '  the  Mind,'  as  though 
it  were  a  something  having  an  actual  independent  exist- 
ence— an  entity,  that  is,  of  *  spiritual  '  or  uncorporeal 
nature.  Consequently  we  find,  spread  abroad  in  all 
directions,  definitions  of  Mind  and  descriptions  of  the 
powers  of  Mind  which,  to  say  the  least,  carry  with  them 
implications  of  a  decidedly  misleading  character. 

It  is  the  common  and  almost  inevitable  practice  of 
substituting  some  abstract  word  for  a  more  cumbersome 
phrase  or  statement,  which  tends  to  keep  up  the  notion  of 
a  distinct  psychical  entity.  Thus  the  word  '  Mind '  is 
generally  used  as  a  collective  designation  for  the  subjective 
states  which  reveal  themselves  to  each  one  of  us  in  con- 
sciousness, and  which  we  infer  to  exist  in  other  beings 
like  ourselves.  But  the  genesis  and  real  legitimate  mean- 
ing of  such  a  term  is  only  too  frequently  forgotten  by 
Fome  writers,  whilst,  by  others,  it  has  never  boon  clearly 
apprehended;  as  a  consequence,  the  word  'Mind'  comes 
to  be  used  most  frequently,  not  as  a  general  abstract 
name  answering  to  no  independent  reality,  but  as  though 
it  corresponded  to  a  real  and  positive  something,  existing 


Chap.  X.]  THE    SCOPE    OF   MIND,  139 

of  and  by  itself.  A  similar  popular  fallacy  attaches  to 
the  common  acceptation  of  the  word  *  Life.'  To  many 
this  also  is  the  name  of  an  entity,  though,  in  reality,  it 
is  only  a  more  general  abstraction,  including  under  it  the 
one  with  which  we  are  now  concerned. 

The  term  '  Mind,'  indeed,  no  more  corresponds  to  a 
definite  self-existing  principle  than  the  word  'Magnetism.' 
This  conclusion,  if  not  a  direct  revelation  of  Conscious- 
ness, is  one  of  those  "  legitimate  inferences  "  to  which 
John  Stuart  Mill  alludes,  in  the  following  passage,  as 
constituting  so  large  a  part  of  human  knowledge. 

'lie  says*: — "  All  theories  of  the  human  Mind  profess  to 
be  interpretations  of  Consciousness.  The  conclusions  of 
all  of  them  are  supposed  to  rest  on  that  ultimate  evidence 
either  immediately,  or  remotely.  What  Consciousness 
directly  reveals,  together  with  what  can  be  legitimately 
inferred  from  its  revelations,  compose  hy  universal  admis- 
sion all  that  we  know  of  the  Mind  or,  indeed,  of  any 
other  thing.'' 

The  various  conscious  or  subjective  states  known  to 
each  one  of  us  are  often  classified  under  three  principal 
categories,  corresponding  to  what  are  commonly  spoken 
of  as  (1)  Sensation  and  Emotion ;  (2)  Intellect,  and 
(3)  Will  or  Volition. 

All  that  we  know  of  Mind  is  derived  (a),  directly  or 
by  inference,  from  our  own  subjective  states  (Subjective 
PsycJiology),  supplemented  by  (b),  what  we  are  able  to 
infer  from  the  words  or  other  actions  of  our  fellow-men 
and  lower  animals,  as  to  the  possession  by  them  of 
similar  states  {Objective  Psychology),  and  (c)  by  what 
we  are  able  to  learn  as  to  the  dependence  of  these 
subjective  states  upon  the  activity  of  certain  parts  of 
our  bodies  and  of  the  bodies  of  other  animals  {Neurology, 
*  "  Examiaation  of  Sir  William  Hamiltoa's  Philosophy,"  p.  107. 


140  THE    SCOPE    OF    MIND. 

or  the  Anatomy,  Physiology,  and  Pathology  of  Nervous 
Systems). 

Our  knowledge  of  Mind  (that  is  of  mental  phenomena) 
differs,  therefore,  altogether  from  our  knowledge  of  all 
other  phenomena.  The  very  existence  of  this  mysterious 
and  inexplicable  class  {a),  so  dissimilar  as  it  seems  from 
everything  else  in  the  universe,  would  have  sufficed  to 
separate  this  branch  of  knowledge  from  all  others,  were  it 
not  the  fact  that,  strictly  speaking,  all  knowledge  what- 
soever of  any  other  natural  phenomena  is  still  but  the 
expression  and  summation  of  our  own  conscious  states — 
were  it  not  the  fact  that  all  other  phenomena  can  only 
be  known  in  terms  of  Mind. 

The  customary  ideal  or  imaginative  embodiment  of 
these  subjective  states  into  a  non-corporeal  or  spiritual 
Ego  is,  from  this  point  of  view,  not  altogether  surprising. 

But  if  we  were  to  lean  implicitly  and  exclusively  upon 
these  direct  revelations  of  Consciousness,  we  must,  as  the 
history  of  philosophy  has  shown,  inevitably  commit  our- 
selves to  a  system  of  universal  scepticism,  needing,  as 
Hume  proclaimed,  a  rejection  of  all  grounds  of  certainty 
for  our  belief  in  an  external  world,  in  body,  and,  indeed,  in 
Mind  as  an  entity — leaving  to  each  one  of  us  a  mere 
fleeting  series  of  Conscious  States  as  representatives  of 
the  totality  of  existence. 

The  absurdity  of  resting  content  with  such  a  conclu- 
sion has  been  commonly  recognized  both  by  philosophers 
and  mankind  in  general.  In  fact,  we  use  our  Conscious- 
ness to  enable  us,  in  imagination  at  least,  to  transcend 
these  direct  revelations  of  Consciousness.  They  are  by 
each  one  of  us  invariably  supplemented  and  modified, 
where  necessary,  by  what  we  deem  to  be  '  legitimate 
inferences' — not  only  in  regard  to  Mind,  apart  from  the 
narrow  yet  all-embracing  region  of  our  own    subjective 


Chap.  X.]  THE    SCOPE    OP    MIND.  141 

states  (that  is,  in  the  spheres  of  Ohjective  Psychology 
and  Neurology),  but  also  in  regard  to  the  whole  system 
of  Natural  Knowledge.  Thus,  as  regards  vital,  mental, 
magnetic,  electric,  thermal,  chemical,  mechanical,  and  all 
other  phenomena,  our  actual  present  '  knowledge '  is 
made  up  of  a  closely-interwoven  potential  hut  intelligible 
fabric  derived  from  actually  existent,  from  remembered, 
described,  or  inferred  Conscious  States  or  relations  be- 
tween them,  together  with  inextricably  intermixed  and 
more  or  less  '  legitimate  inferences  '  therefrom. 

Our  knowledge  of  what  is  called  Objective  Psychology, 
as  well  as  our  knowledge  of  the  relation  of  subjective 
states  generally  to  the  activity  of  the  Nervous  System,  as 
deduced  from  its  Anatomy,  Physiology,  and  Pathology 
(the  knowledge,  that  is,  which  contributes  so  largely  to 
make  up  what  we  know  concerning  Mind,  or  mental 
phenomena)  stands,  therefore,  on  precisely  the  same 
foundation  as  our  knowledge  of  Magnetism — that  is  of  the 
magnetic  phenomena  presented  by  different  forms  of  iron. 
The  word  '  Magnetism  '  is  one  which  has  come  into  use 
in  much  the  same  way  as  the  word  *  Mind,'  although  it 
is  true  that  the  connotation  of  the  latter  is  wider  in  kind 
and  degree,  since  under  it  we  include  not  only  what  are 
considered  '  legitimate  inferences '  from  conscious  states 
(our  only  sources  of  knowledge  concerning  Magnetism), 
but  also  these  very  conscious  states  themselves.  It  is  on 
this  latter  ground  only — though  of  course  it  is  one  of 
fundamental  importance — that  our  knowledge  of  '  Mind ' 
differs  from  what  we  know  generally  in  regard  to  all 
other  natural  phenomena. 

From  a  basis  of  agreement,  therefore,  as  to  the  acknow- 
ledged insufficiency  of  the  direct  revelations  of  Conscious- 
ness in  any  branch  of  natural  knowledge,  it  seems  to 
the  writer  incontestible  that  the  same  kind  of  evidence  as 


142  THE    SCOPE    OF    MIND. 

that  wliicli  assures  us  of  the  existence  of  our  own  bodies 
and  of  the  properties  of  external  things  (viz.,  inferences 
from  conscious  states),  should  guide  us  in  the  study,  and 
as  to  the  conclusions  deducihle  from  our  own  mental 
phenomena  and  those  of  other  living  beings.  An  attentive 
consideration,  however,  of  such  evidence  altogether  fails 
to  assure  us  of  the  existence  of  *  the  Mind'  as  a  self- 
existent  entity.  It  is,  indeed,  quite  the  reverse.  Very 
many  of  those  who  are  most  entitled  to  form  a  judgment 
upon  this  subject,  regard  it  as  a  *  legitimate  inference' 
from  existing  knowledge  that  Conscious  States,  and,  indeed, 

*  mental  phenomena '  generally,  are  dependent  upon  the 
properties  and  molecular  activities  of  nerve-tissues,  just  as 

*  magnetic  phenomena '  are  dependent  upon  the  properties 
and  molecular  actions  of  certain  kinds  or  states  of  iron. 
Regarded  as  ultimate  facts,  we  are  just  as  impotent  to 
'explain'  the  relation  or  nexus  of  causation  existing 
between  Magnetic  Phenomena  and  the  one  set  of  molecu- 
lar activities,  as  we  are  to  explain  the  causation,  direct  or 
indirect,  of  Conscious  States  by  other  molecular  activi- 
ties. The  mere  fact  that  we  are  each  of  us  conscious  of 
the  existence  of  mental  or  subjective  states,  inscrutable 
and  ultimate  as  these  must  always  be,  certainly  cannot 
be  supposed  to  give  any  knowledge  of  '  Mind  '  as  a  self- 
existent  entity. 

Some  of  those  who  seek  to  expound  mental  phenomena 
from  a  scientific  stand-point,  have  not  always  been  suffi- 
ciently careful  to  suit  their  language  to  their  views. 
This  should,  however,  be  done  somewhere ;  and,  if 
not  elsewhere,  certainly  in  a  preliminary  disquisition, 
in  order  that  there  may  be  no  room  for  doubt  as  to  an 
author's  meaning  when  he  uses  the  term  '  Mind.*  With 
this  end  in  view  some  further  remarks  and  explanations 
will  now  be  given. 


Chap.  X.]  THE    SCOPE    OF    MIND.  143 

One  of  the  principal  errors,  wliicli  the  metaphysical 
conception  of  Mind  as  an  entity  entails,  is  that  '  mental 
phenomena'  are  supposed  to  be  limited  or  bounded  by  the 
sphere  of  Consciousness.  That  this  has  been  the  view  of 
the  great  majority  of  philosophers  any  student  of  their 
"Writings  will  easily  discover.  Thus  Consciousness  is  said 
by  one  of  them,  to  be  "  the  fundamental  condition  of  all 
intelligence,"  whilst  another  holds  that,  "of  all  the 
present  operations  of  the  mind,  consciousness  is  an 
inseparable  concomitant.'*  Such  doctrines  are,  indeed, 
legitimate  deductions  from  the  metaphysical  view  concern- 
ing Mind,  though  its  inadequacy  is  now  fully  recognized 
not  only  by  physiologists,  but  also  by  some  modern 
psychologists.  Thus  Professor  Bain,  after  speaking 
of  Mind  in  its  three  fundamental  capacities.  Feeling, 
Action  (Yolition),  and  Thought,  says* :  "Consciousness 
is  inseparable  from  the  first  of  these  capacities,  but 
not  as  it  appears  to  me,  from  the  second  or  the  third. 
True,  our  actions  and  thoughts  are  usually  conscious,  that 
is,  are  known  to  us  by  an  inward  perception ;  but  the 
consciousness  of  an  act  is  manifestly  not  the  act,  and, 
although  the  assertion  is  less  obvious,  I  believe  that  the 
consciousness  of  a  thought  is  distinct  from  the  thought." 

The  sphere  of  *  mental  phenomena '  cannot,  indeed,  be 
circumscribed  by  the  sphere  of  Consciousness,  and  the 
recognition  of  this  fact  necessitates  the  absolute  rejection 
of  the  word  '  Mind '  in  its  old  signification,  and  compels 
us  to  include  under  this  collective  abstract  term  multitudes 
of  processes  or  nerve  actions,  which  now,  so  far  as  we  are 
aware,  have  no  correlative  subjective  aspects,  though  they 

♦  **  The  Senses  and  the  Intellect,"  p.  1.  The  language  of  the 
three  statements  there  given  by  way  of  definition  of  Mind,  seems 
to  imply  a  beUef  in  a  self- existent  something,  able  to  Feel  and 
Think,  and  capable  of  Acting. 


144  THE    SCOPE    OF    MIND. 

may  intervene  as  indubitable  links  or  constituents  of 
*  mental  phenomena.'  There  need  be  the  less  hesitation 
in  admitting  this  latter  conclusion  from  the  fact  that  it  is 
one  which  each  of  us  can  so  easily  verify  for  himself. 

We  are  frequently  conscious  of  the  first  term  of  some 
process  of  thought,  and  we  become  aware  of  the  last, 
whilst  those  which  intervene,  numerous  though  they 
may  be,  do  not  in  the  least  reveal  themselves  to  our 
consciousness.  We  seek,  for  instance,  to  recall  some 
name  or  word  at  the  time  forgotten.  We  are  conscious 
only  of  a  sense  of  ^effort'  which  may,  at  the  time,  be 
fruitless,  and  yet,  after  a  period,  in  which  we  have  been 
thinking  of  other  things,  the  desired  word  or  name 
suddenly  declares  itself  in  our  consciousness.  We  may 
say  with  Dr.  Carpenter  :  ''Now  it  is  difficult,  if  not  im- 
possible, to  account  for  this  fact  upon  any  other  supposition 
than  that  a  certain  train  of  action  has  been  set  going  in 
the  cerebrum  by  the  voluntary  exertion  which  we  at  first 
made ;  and  that  this  train  continues  in  movement  after 
our  attention  has  been  fixed  upon  some  other  object  of 
thought,  so  that  it  goes  on  to  the  evolution  of  its  result, 
not  only  without  any  continued  exertion  on  our  parts  but 
also  without  our  consciousness  of  any  continued  activity." 
And  that  some  such  view  as  this  has  commended  itself 
to  so  distinguished  a  philosophical  thinker  as  the  late 
J.  S.  Mill  may  be  gathered  from  the  following  quotation 
in  reference  to  parallel  phenomena.  He  says*:  "If  we 
admit  (what  physiology  is  rendering  more  and  more 
probable)  that  our  mental  feelings  as  well  as  our  sensations 
have  for  their  physical  antecedents  particular  states  of  the 
nerves,  it  may  well  be  believed  that  the  apparently 
suppressed  links  in  a  chain  of  association,  those  which 
Sir  William  Hamilton  considers   as  latent,  really  are  so, 

*  "  Examination  of  Sir  Wm.  Han.ilton's  Philosophy,"  p.  285. 


Chap.  X.]        THE  SCOPE  OF  MIND.  145 

that  they  are  not  even  momentarily  felt ;  the  chain  of 
causation  being  continued  only  jphysically,  by  one  organic 
state  of  the  nerves  succeeding  another  so  rapidly  that  the 
state  of  mental  consciousness  appropriate  to  each  is  not 
produced.''^ 

It  is,  indeed,  certain  that  multitudes  of  nerve  actions 
having  no  subjective  side  (that  is,  which  are  unaccom- 
panied by  phases  of  consciousness),  form  links  or  integral 
parts  of  our  momentarily  occurring  mental  states,  and 
that  such  mere  objective  phenomena  powerfully  assist  in 
determining  our  so-called  mental  acts.  Nay,  more,  it 
seems  almost  certain  that  the  greater  part  of  our  Intel- 
lectual Action  proper  (that  is  Cognition  and  Thought  as 
opposed  to  Sensation)  consists  of  mere  nerve  actions  with 
which  no  conscious  states  are  associated.  And,  lastly, 
each  one  of  us  may  have  had  frequent  occasion  to  notice 
that  states  of  Feeling  which  at  first  accompany  unfamiliar 
Muscular  Movements,  after  a  time  no  longer  reveal  them- 
selves in  Consciousness,  that  is,  when  such  movements 
have  by  dint  of  frequent  repetition  become  easy  of  per- 
formance. Thus,  rapid  and  unconscious  Automatic  Actions 
are  constantly  tending,  in  our  own  experience,  to  take  the 
place  of  slower  and  more  consciously  executed  Yolitional 
Movements. 

From  this,  as  well  as  much  more  which  might  be  said, 
it  would  appear  that  those  nerve  actions  attended  by 
conscious  states  (to  which  latter  correlatives  philosophers 
have  been  accustomed  to  restrict  the  words  '  Mind ' 
and  '  mental  phenomena ' )  constitute,  in  reality,  only  a 
very  small  fraction  of  the  sum  total  of  nervous  states  or 
actions  which  are  now  known  to  be  comprisad  among 
{a)  the  initial  nervous  phenomena  leading  to  Sensation 
and  Emotion,  among  {b)  the  intermediate  links  of 
Thought  and  Imagination,  among  (c)  the  beginniugs  of 


146  THE    SCOPE    OF    MIND. 

Desire,  and  which  exist  (d)  as  the  incitations  to,  or 
accompaniments  of,  Volitional  Action.  But,  if  this  he 
true,  what  becomes  of  the  metaphysical  entity  callerl 
*  Mind '  ? 

Thus,  it  would  appear  that,  if  we  are,  as  so  many 
philosophers  tell  us,  to  regard  the  sphere  of  Mind  as 
co-extensive  with  the  sphere  of  Consciousness,  we  should 
find  *Mind'  reduced  to  a  mere  imperfect,  disjointed, 
serial  agglomeration  of  feelings  and  conscious  states  of 
various  kinds — while  the  multitudes  of  initial  or  inter- 
mediate nerve  actions  (which  serve  to  bind  those  other 
nerve  actions  commonly  associated  with  conscious  corre- 
latives into  a  complex,  continuous  and  coherent  series) 
would  have  no  claim  to  be  included  under  this  category. 

For  these  and  other  reasons,  we  feel  ourselves  driven 
to  the  conclusion  that  the  common  notion  as  to  what 
should  be  included  under  the  term  Mind,  is  one  which  is 
altogether  erroneous,  and  such  notion  ought  clearly  enough 
to  be  given  up,  unless  some  warrantable  extension  of  the 
meaniijg  of  the  narrower  term  Consciousness  should  per- 
mit the  rectification  to  be  made  in  this  direction. 

It  would  seem  to  most  persons  impossible  so  to  widen 
the  signification  of  the  word  Consciousness,  as  to  make  it 
co-extensive  with  unconscious  nerve  actions,  though  some 
such  proposition  seems  suggested  by  Professor  Bain  when 
he  says  :*  *'  We  assume  as  a  fundamental  fact,  that  with 
nervous  action  feeling  begins."  This  is  certainly  a  large 
assumption,  and  one  which  it  is  ditticult  to  admit,  though 
a  notion  of  the  same  kind  was,  several  years  ago,  advocated 
by  G.  II.  Lewes, t  who  holds  steadfastly  to  the  notion  that 
sensibility  is  the  property  of  ganglionic  nerve  tissue  in 
general,  even  though  the  action  of  such  ganglionic  tissue 
*  *•  Mind  and  Body,"  p.  53.      f  "  Physiology  of  Common  Life.'* 


Chap.  X.]  tHE    SCOPE    OF    MIND.  147 

may  not  reveal  itself  by  any  phases  of  Consciousness  what- 
soever.* To  have  a  feeling  of  which  we  are  not  conscious 
will  seem  to  most  of  us  a  contradiction  in  terms.  J.  S. 
Mill  was  evidently  of  this  opinion,  since  he  saysif  "To 
feel,  and  not  to  know  that  we  feel,  is  an  impossibility." 
What,  it  may  be  asked,  is  the  nature  of  an  unconscious 
*  sensation'  ?  Language  employed  in  this  way  seems  to 
become  meaningless,  and,  in  the  writer's  opinion,  cannot 
be  justified.  If  an  impression  receives  none  of  our 
Attention,  that  is  only  saying  in  other  words,  that  we  are 
not  conscious  of  it  or  do  not  feel  it.  In  such  a  case  we 
have  no  reasonable  warrant  for  calling  such  an  impression 
a  '  sensation.'  No  excuse  for  such  language  appears  to  bo 
found  in  the  mere  fact  that  there  are  different  degrees 
or  intensities  of  Consciousness,  and  that  nerve  actions 
without  feeling  cannot  be  sharply  separated  from  nerve 
actions  which  are  accompanied  by  feeling.  It  should  be 
clearly  recognized  that  this  kind  of  reasoning  tends  to 
give  us  no  definite  resting  point :  from  such  a  basis  we 
might  (and  in  fact  ought  logically)  to  go  on  to  postulate 
the  existence  of  Consciousness  in  plants,  and  even  in 
inanimate  things — since  the  demarcation  between  Con- 
sciousness and  the  absence  of  it,  is  more  radical  than  that 
which  separates  nerve  tissues  from  other  living  tissues, 
and  living  from  not  living  matter.  J  Although,  however, 
as  we  may  freely  concede,  the  phrase  '  unconscious  sensa- 
tion' is  far  from  being  meaningless  or  unjustifiable  from 
the  point  of  view  of  a  purely  speculative  philosophy,§  its 

*  Since  the  above  was  written,  G.  H.  Lewes  has  published  hia 
"Physical  Basis  of  Mind,"  1877, in  which  his  views  are  more  elabo- 
rately developed  and  supported. 

t  "Examination  of  Sir  Wm.  Hamilton's  Philosophy,"  p.  132. 

X  "  Beginnings  of  Life,"  vol.  i.  p.  79  ;  vol.  ii.  p.  77. 

§  See  A.  Barratt's  "  Physical  Ethics,"  1869,  p.  112. 


148  THE    SCOPE    or    MIND. 

use  tends  to  introduce  confusion  into  a  subject  the  natural 
complexity  of  which  ah'eady  makes  it  sufficiently  baffling. 
There  may  be  nascent,  ill-defined,  or  abortive  subjective 
sides  to  many  nerve  actions,  but,  if  these  do  not  answer 
in  ourselves  to  what  we  know  as  Consciousness,  it  should 
not  be  said,  that  *  sensibility '  is  an  appanage  of  such 
nerve  actions. 

If,  however,  we  are  compelled  to  believe  that  Conscious- 
ness is  not  co-extensive  with  the  sphere  of  *  Mind,'  in 
the  ordinary  acceptation  of  these  terms,  and  that  no 
expedient  modification  of  the  meaning  of  the  word 
Consciousness  could  make  it  so,  then  in  face  of  the  now 
admitted  fact  concerning  the  frequent  interpolation  of  what 
J.  S.  Mill  called  mere  '*  organic  states  of  the  nerves," 
or  unconscious  nerve  actions,  as  integral  parts  of  mental 
processes — only  one  other  course  lies  open  to  us.  We 
must  widen  the  signification  of  the  term  '  Mind '  itself. 

This  is  no  question  of  choice,  but  one  of  absolute 
necessity.  The  meaning  of  the  word  '  Mind  '  must  be  very 
considerably  enlarged,  so  as  to  enable  us  to  comprise  under 
its  new  and  more  ample  signification  the  results  of  all  nerve 
actions,  other  than  those  of  outgoing  currents.  We 
should  thus  include  as  '  mental  phenomena,'  the  functional 
results  of  all  nerve  actions  on  the  side  of  ingoing  currents 
and  in  the  nerve  centres — whether  these  nerve  actions 
are  accompanied  by  a  recognizable  conscious  phasis,  or 
whether  they  form  what  appear  to  be  mere  physical  links 
(or  "  organic  states  of  the  nerves")  between  other  nerve 
actions  which  are  unquestionably  in  relation  with  definite 
Conscious  States. 

We  thus  include  under  the  word  '  Mind '  all  those  well- 
known  results  of  nerve  action  which  are  comprised  under 
the  general  categories  of  (1)  Feeling,  Sensation  or 
Emotion,  (2)  Intelhgcnce,  Instinct  or  Thought,  and  (3) 


Chap.  X.]  THE    SCOPE    OF    MIND.  149 

Attention,  Volition  or  Will ;  and  we  do  not  exclude  the 
multitudinous  results  of  mere  unconscious  nerve  actions, 
which  constitute  so  many  integral  parts  of  our  mental 
life — interpolating  themselves  from  moment  to  moment, 
and  having  their  origin  in  various  parts  of  our  nervous 
system.  The  functional  results  of  outgoing  currents, 
however,  lie  wholly  beyond  the  sphere  of  mind  :  they 
terminate  in  such  physico-vital  phenomena,  as  the  con- 
traction or  the  arrest  of  contraction  in  Muscles,  and  the 
stimulation  or  the  reverse  of  Glandular  Activity — events 
which  are  in  no  sense  mental,  though  brought  about  by 
nervous  influence.  They  are  purely  physical  phenomena, 
and  are  taken  cognizance  of  by  means  of  special  impres- 
sions made  upon  and  conducted  to  the  Cerebrum  by  such 
ingoing  or  sensory  nerves  as  are  in  relation  with  the  moving 
parts  or  secretory  organs.* 

Here  a  difficulty  at  once  presents  itself.  It  will  doubt- 
less be  said  on  all  sides  that  we  cannot  rightly  group  the 
various  Conscious  States  which  accompany  certain  nerve 
actions  (subjective  phenomena)  with  mere  unconscious 
nerve  actions  (objective  phenomena).  These  two  groups 
of  phenomena,  it  is  always  said,  are  separated  from  one 
another  by  what  appears  to  be  utter  dissimilarity  of  nature, 
as  typified  by  the  fundamental  contrast  of  Subject  and 
Object  (the  Ego  and  the  Non-Ego). 

This  is  an  objection  based  upon  our  ignorance  as  to  the 
exact  genetic  relation  existing  between  subjective  states 
and  the  bodily  conditions  (or  nervous  actions)  on  which 
they  seem  to  be  dependent.  It  is  probably  due  to  an 
equal  extent  to  a  temporary  forgetfulness  on  the  part  of 
those  who  advance  it,  that  we  are  as  much  in  the  dark  as 
to  the  real  nature  of  Motion  as  we  are  about  the  real  mode 

*  These  questions  as  to  the  relation  of  '  outgoing  currents '  to 
Mind  will  be  fully  discussed  in  Chap.  xxvi. 


150  THE    SCOPE    OF    MIND. 

of  origin  of  Feeling.  Motions,  whether  molecular  or  other, 
we  know  only  by  their  effects  upon  us,  that  is,  in  terms  of 
Feeling.  Who,  therefore,  is  to  declare  that  there  can  be 
no  kinship  between  that  which  is  the  cause  of  Feeling 
and  the  molecular  movements  of  certain  nerve  tissues, 
when,  as  to  the  cause  of  Feeling,  knowledge  other  than 
that  which  comes  from  inference,  is,  from  the  very  nature 
of  the  problem,  for  us  impossible,  and  when  we  con- 
fessedly know  nothing  concerning  molecular  movements 
other  than  what  we  can  learn  through  Feeling. 

There  seems,  therefore,  no  real  room  or  occasion,  from 
a  scientific  point  of  view,  for  the  protests  which  some 
will  assuredly  make  against  this  necessary  grouping  of  (a) 
the  conscious  states  and  certain  parent  nerve  actions,  with 
(b)  other  mere  unconscious  nerve  actions,  which  are  con- 
tributory to,  rather  than  directly  associated  with,  conscious 
states — as  the  constituent  phenomena  Mind  in  its  new 
and  altogether  broader  acceptation.  That  the  two  classes 
of  nerve  actions  referred  to  are  in  reality  separated  by  no 
arbitrary  line,  and  that  the  more  simple  (h)  are  connected 
by  innumerable  gradations  with  the  more  complex  (a)  is 
an  assumption  favoured  by  all  who  believe  in  the  philo- 
sophy of  Evolution.*  Such  persons  will,  therefore,  more 
easily  see  that  '  mental  phenomena,'  as  above  defined, 
correspond  to  a  coherent  rather  than,  as  of  old,  to  an 
incoherent  and  non-consecutive  assemblage  of  processes. 

Some  such  change  is  inevitable,  and  we  of  the  present 
generation  must  bear  the  discomfort  and  inconvenience 
naturally  arising  from  an  altered  meaning  of  the  term 
Mind,  in  order  that  those  who  follow  may  reap  the  benefit 
which  will  after  a  time  result  from  the  rectification. 
Knowledge   is   progressive,  and,  if  old  terms  are  to  be 

*  See  Prof.  ISTageli's  Address  at  Munich  on  "The  Limits  of 
Natural  Knowledge,"  as  translated  in  "Nature,"  Oct.  25, 1877, p. 661. 


Chap.  X.]  THE    SCOPE    OF    MIND.  151 

retained,  their  implications  must  from  time  to  time  be 
amended,  in  order  that  further  progress  may  be  made  more 
easy  or  even  possible. 

Those  who  take  the  step  above  indicated,  will  recognize 
another  truth  which  has  been  already  implied.  They  will 
find  themselves  logically  compelled  to  depart  still  further 
from  commonly  recognized  views.  On  strict  enquiry,  it 
will  be  seen  that  the  notion  that  the  Brain  is  the  exclusive 
*  organ '  of  Mind  can  no  longer  be  entertained.  This 
view  was,  indeed,  too  broad  to  be  justified  by  the  old 
philosophy,  since  only  a  very  small  part  of  the  nerve 
actions  taking  place  in  the  different  ganglia  entering 
into  the  composition  of  the  human  brain  are  attended 
by  Conscious  States.  But,  if  the  seat  assigned  to  Mind 
was  formerly  much  wider  than  physiology  could  warrant, 
it  now,  on  the  other  hand,  becomes  much  too  narrow. 

This  will  be  seen  to  be  a  necessary  consequence  of 
including  under  the  term  •'  Mind '  a  multitude  of  the 
unconscious  nerve  actions  occurring  in  the  Brain.  For 
it  is  impossible  to  draw  any  valid  line  of  demarcation 
between  many  unconscious  nerve  actions  taking  place  in 
the  brain  of  man  or  any  lower  animal,  and  others  (with 
which  they  are  continuously  or  genetically  related)  in  the 
spinal  cord,  or  in  any  of  the  ganglionic  masses  in  different 
parts  of  the  body.  The  division  of  the  Nervous  System 
into  Brain,  Spinal  Cord,  and  Sympathetic  System  is  one 
which,  though  justifiable  enough  on  anatomical  grounds,  is 
much  less  so  from  a  physiological  point  of  view.  The 
Nervous  System  is  really  one  and  indivisible,  so  that,  if, 
with  certain  reservations,  unconscious  nerve  actions  occur- 
ring in  the  Brain  are  to  be  regarded  as  '  mental  pheno- 
mena,' we  can  find  no  halting  point  short  of  including 
under  the  same  category  any  unconscious  nerve  actions  of 


152  THE    SCOPE    OF    MIND. 

a  similar  order,  wheresoever  they  may  occur.  In  this 
sense,  therefore,  almost  the  whole  Nervous  System  would 
have  to  be  regarded  as  the  *  organ '  of  Mind,  while  the 
Brain  should  be  regarded  as  merely  its  principal  com- 
ponent part. 

Views  closely  similar  to  those  above  set  forth  were 
advanced  by  the  writer  in  1870,  when  he  said  :*  "  Let  us 
openly  profess  what  has  been  tacitly  implied  by  many. 
Instead  of  supposing  that  Mind  and  Consciousness  (in  its 
ordiuary  acceptation)  are  co-extensive,  let  us  make  Mind 
include  all  unconscious  nerve  actions  as  well  as  those  which 
are  attended  by  Consciousness  ....  We  must  inevitably 
come  to  this,  and  the  doctrine  of  *  unconscious  cere- 
bration *  has  served  to  pave  the  way  for  it See- 
ing that  Mind,  even  in  its  ordinary  acceptation,  is  the 
product  of  all  '  potential '  as  well  as  of  all  realized, 
knowledge,  the  word  cannot  without  the  intervention  of  a 
fundamental  error  be  considered  as  a  convertible  term  for 
realized  or  realizable  knowledge  only.  That  which  is 
realizable  now,  or  capable  of  being  recalled  to  conscious- 
ness, may,  and  often  does,  after  a  time  cease  to  be  so,  and 
yet  the  essential  nerve  actions  themselves  may  still  go  on, 
and  none  the  less  surely  work  their  influence  upon  our 
fleeting  succession  of  conscious  states.  Thus  has  it  been 
with  the  race,  and  thus  is  it  with  the  individual.  And 
shall  we  cease  to  call  a  given  nerve  action  mental,  when 
by  frequent  repetition  it  has  become  so  habitual  that  it  no 
longer  arouses  Consciousness  ?  "  Transitions  from  con- 
scious nerve  actions  to  unconscious  nerve  actions  are  habitu- 
ally taking  place  during  the  education  of  the  individual, 
and  the  development  of  the  nervous  system  in  each  one  of 
us,  and  "  the  more  fully  such  phenomena  are  recognized 
as  parts  of  an  orderly  succession  by  which  alone, 
*  '*  Journal  of  Mental  Science,"  Jan.,  p.  622. 


CuAP.  X.]  TFIE    SCOPE    OV    MIND.  153 

greater  and  greater  complexities  of  thought  and  feeling 
are  rendered  possible,  the  more  will  it  become  evident  that 
the  sphere  of  mind  cannot  at  any  time  be  ciicumscribed 
by  the  then  present  or  possible  states  of  Consciousness, 
the  more  it  is  obvious  that  in  our  conception  of  mind  we 
should  also  include  all  past  stages  of  Consciousness, 
which  now  in  the  form  of  unconscious  nerve  actions 
are,  from  moment  to  moment,  manifesting  themselves 
potentially,  if  not  actually,  in  all  our  present  Thoughts, 
Feelings,  and  Volitions." 

Certain  qualifications  of  this  doctrine  are  now  intro- 
duced, since,  for  reasons  which  wdll  be  more  fully  con- 
sidered in  later  chapters,  those  tracts  of  the  Nervous 
System  exclusively  concerned  with  the  passage  of  *  out- 
going currents '  are  now  deemed  to  have  no  more  claim 
to  be  regarded  as  parts  of  the  *  organ '  of  Mind  than 
has  the  Muscular  System  itself,  with  which  they  are  in 
immediate  relation. 

The  views  above  sketched,  are  different  from  those 
commonly  entertained  by  physiologists,  and  they  also 
differ,  in  one  or  other  respect,  from  those  of  modern  British 
philosophers  such  as  Spencer,  Lewes  and  Bain.  They 
differ,  however,  still  more  widely  from  the  views  of  other 
philosophical  writers  who,  not  having  emancipated  them- 
selves from  the  mere  metaphysical  doctrines  concerning 
Mind,  habitually  regard  it  as  an  entity,  and  speak  of 
*  the  Mind '  using  the  Brain  as  its  instrument. 

This  latter  doctrine,  which  still  counts  a  wide  circle 
of  adherents,  and  is  likely,  perhaps,  to  do  so  for  some 
time,  has  been  aptly  met  by  Professor  Bain.  He  says  :* 
"  In  the  first  place  it  assumes  that  we  are  entitled  to 
speak  of  Mind  apart  from  body,  and  to  af&rm  its  powers 

*«  Mind  and  Body,"  p.  130. 


Ie54  THE    SCOPE    OF    MIND. 

and  properties  in  that  separate  capacity.  But  of  mind 
apart    from    body   we   have    no    direct   experience,    and 

absolutely  no  knowledge In  the  second  place  we 

have  every  reason  for  believing  that  there  is,  in  company 
with  all  our  mental  processes,  an  unbroken  material 
succession.  From  the  ingress  of  a  sensation  to  the  out- 
going responses  in  action,  the  mental  succession  is  not  for 

an  instant  dissevered  from  a  physical  succession 

It  would  be  incompatible  with  everything  we  know  of 
cerebral  action,  to  suppose  that  the  physical  chain  ends 
abruptly  in  a  physical  void,  occupied  by  an  immaterial 
substance ;  which  immaterial  substance,  after  working 
alone,  imparts  its  results  to  the  other  edge  of  the  physical 
break,  and  determines  the  active  response — two  shores  oi 
the  material  with  an  intervening  ocean  of  the  immaterial.'* 
The  difficulties  in  working  such  a  hypothesis  are  in  fact 
extreme,  even  if  it  had  not  been  negatived  by  the  many 
other  considerations  referred  to  in  previous  pages. 

In  treating  of  '  the  Brain  as  an  organ  of  Mind,'  there- 
fore, it  will  be  understood  that  we  use  the  word  '  organ  ' 
merely  in  the  sense  that  it  is  a  part  whose  molecular 
changes  and  activities,  constitute  the  essential  correlatives 
of  those  phases  of  Consciousness  known  as  Sensations, 
Emotions,  Thoughts,  and  Volitions,  as  well  as  of  a  con- 
siderable part  of  the  sum  total  of  those  other  related 
nerve  actions  which  are  unattended  by  Consciousness,  and 
whose  results  form,  in  accordance  with  the  views  above 
stated,  so  large  a  proportion  of  the  phenomena  compre- 
hended under  the  general  abstract  word  '  Mind.' 

From  what  has  been  already  said,  it  will  be  seen  that 
the  study  of  '  mental  phenomena'  has  to  be  carried  on  in 
many  different  directions,  and  that  it  is  one  which  is  beset 
with  peculiar  difficulties.     The  following  table  or  diagram 


Chap.  X.] 


THE    SCOPE    OF    MTND. 


155 


indicates  the  principal  kinds  of  data  which  require  to  be 
combined,  and  more  or  less  fused,  in  order  to  give  birth 
to  a  legitimate  Psychology  or  true  science  of  Mind, 


^^io^  o^ndClas,,^ 


^*<!lteso/Co.^.,,,^;-^aS. 


c^ 


'^^ 

-^0%%^^ 


% 


■^'^^ 


v-se" 


o^' 


.■^^ 


These  three  departments  supply  data  almost  equally 
important.  To  neglect  the  facts  supplied  by  Neurology 
would  be  about  as  unreasonable  as  to  dismiss  the  legitimate 
study  of  Subjective  Psychology,  and  certainly  is  on  no 
grounds  to  ba  defended  by  those  who  do  not  refuse  to 
include  the  study  of  Objective  Psychology — and  are  thus 
willing  to  take  account  of  the  data  obtainable  as  to  the 
conscious  states  of  animals  and  of  human  beings  other 
than  themselves.  For,  if  a  departure  is  once  made  from 
the  sphere  of  the  subjective,  the  data  of  Neurology  must 
be  admitted  to  constitute  as  important  a  division  of  the 
science  of  Mind  as  those  derived  from  Objective  Psycho- 
logy— from  which  they  differ  more  in  degree  than  in 
kind. 


CHAPTER  XI. 

REFLEX  ACTION   AND   UNCONSCIOUS    COGNITION. 

The  nature  of  a  Reflex  Action  has  been  already  indicated, 
and  tlie  tissue  elements  usually  concerned  in  such  an 
elementary  nervous  operation  have  been  described.  They 
consist  of  ingoing  fibres  continuous  in  a  Nerve  Centre  with 
so-called  *  sensory '  nerve  cells,  vvhich  in  their  turn  are 
in  communication  with  some  group  or  groups  of  *  motor ' 
nerve  cells,  whence  issue  outgoing  fibres  for  the  trans- 
mission of  stimuli  to  muscles. 

Such  groups  of  tissue  elements  variously  connected 
together  are  continually  increasing  in  definiteress  and  num- 
ber during  the  course  of  structural  development,  as  well  as 
during  the  whole  time  in  which  the  '  education  '  of  animal 
organisms  progresses.  The  cellular  elements  are  aggre- 
gated into  Ganglia  of  different  sizes,  and,  by  reason  of 
their  close  approximation  in  these  bodies,  the  establish- 
ment of  structural  connections  between  those  cells  which 
are  functionally  related,  either  on  the  side  of  '  impi-es- 
sion  '  or  on  that  of  *  reaction,'  is  doubtless  facilitated. 

Thus  it  seems  to  result  from  the  very  nature  of  nerve 
tissues  and  their  mode  of  development,  that  variations 
in  the  kind  and  combination  of  impressions  acting  upon 
any  particular  organism,  as  part  of  its  life  phenomena, 
become  by  slow  degrees  organically  linked  to  different 
and   severally  appropriate  motor  results.     The  organism 


CiiAP.  XI.]  UNCONSCIOUS    COGNITION.  157 

*  learns '  to  discriminate  one  impression  from  another, 
either  unconsciously  or  consciously — as  we  are  compelled 
to  infer,  from  the  difFeient  nature  of  its  motor  responses 
and  the  suitability  of  each  as  an  answer  to  the  impression 
which  it  follows.  Thus  '  discrimination  '  comes  to  be  an 
essential  result  or  concomitant  of  the  action  of  even  the 
simplest  nerve  tissues.* 

And  as  ^discrimination'  is  generally  recognized  by 
philosophers  to  be  the  root  faculty  or  most  fundamental 
manifestation  of  Intelligence,  we  shall  find  in  the 
phenomena  of  Reflex  Action,  now  about  to  be  illustrated,  a 
further  strong  support  for  the  view  that  the  nervous 
system  generally  is  to  be  regarded  as  the  Organ  of 
Mind. 

In  most  lower  animals,  as  we  have  seen,  several  separate 
Nerve  Centres,  or  Ganglia,  constitute  the  main  subdivisions 
of  the  nervous  system.  In  animals  like  the  Centipede, 
these  ganglia  are  very  numerous,  and  distinct  from  one 
another ;  in  others,  such  as  the  Grasshopper,  several 
become  fused  at  intervals,  so  that  separate  ganglia  are 
less  numerous  ;  while  in  Vertebrate  animals,  as  we  have 
seen,  the  fusion  is  carried  still  further.     In  the  Fish,  the 

*  Something  very  hke  organic  discrimination  may  occur  in 
Plants.  A  writer  in  "Nature"  (June  26, 1873,  p.  164)  cites  what  may 
be  regarded  as  an  instance  of  this.  He  says:  "The  Ivy  Linaria 
grows  on  an  old  wall;  its  flowers  and  the  flower-stalks  stand  out 
for  the  sun  and  Insects  to  visit  the  little  *  snap-dragon.'  But  no 
sooner  does  the  corolla  fall  than  the  peduncle  begins  to  curve  in- 
wards to  the  wall,  and  usually  contrives  to  tuck  its  seed-vessel  well 
into  the  brickwork  again."  An  action  like  this  may  perhaps  be 
the  result  of  an  organic  impulse  or  tendency  fostered,  if  not  engen- 
dered, by  '  natural  selection.'  And  as  the  observer  intimates,  there 
are  certain  obvious  relations  between  such  a  process  and  some  of 
the  instinctive  actions  of  animals  in  connection  with  ovi-position. 
8 


158  REFLEX   ACTION    AND 

Eeptile,  and  other  Vertebrates,  the  separate  ventral  gan- 
glia of  the  Centipede  are  represented  functionally  by  a 
continuous  cord-like  aggregation  of  fused  centres,  which 
occupy  the  median  line  in  the  dorsal  aspect  of  the  body. 

The  lower  the  organism,  the  more  independent  is  the 
functional  activity  of  its  several  nerve  ganglia,  while  the 
higher  the  animal  in  type  and  scale  of  organization,  the 
more  closely  knit  together  are  the  activities  of  these  several 
parts  of  the  nervous  system.  Even  in  Man  himself,  how- 
ever, we  have  frequent  evidence  of  the  independent  action 
of  more  or  less  limited  regions  of  the  nervous  system. 
This  is  the  case,  for  instance,  in  winking,  sneezing, 
coughing,  swallowing,  which  are  all  of  them  reflex  or 
*  automatic  '  actions.  The  latter  name  has  been  given  on 
account  of  the  machine-like  regularity  with  which  such  acts 
are  performed — independently  of  all  conscious  guidance. 

The  existence  and  mechanism  of  '  reflex  actions  '  were 
first  distinctly  referred  to  by  David  Hartley  in  1748  ;  they 
were  more  definitely  described  by  Prochaska  in  1784 ; 
though  it  was  Marshall  Hall  who,  some  fifty  years  later, 
first  clearly  recognized  and  elucidated  their  real  impor- 
tance. Since  his  time  our  knowledge  of  these  actions  has 
been  widened  in  all  directions  by  the  labours  of  many 
physiologists. 

The  fact  that  each  Ganglion  in  one  of  the  lower 
animals  constitutes  an  independent  centre  for  reflex 
actions,  and  that  the  movements  to  which  it  gives  rise  are 
always  co-ordinated  and  adaptive  in  their  characters,  was 
experimentally  established  by  Duges. 

This  naturalist  made  some  interesting  observations  on 
the  '  Mantis,'  a  large  insect  having  some  resemblance  to  a 
Cricket  which  is  very  common  in  the  south  of  France  and 
in  Italy.  The  creature  is  notable  for  a  long,  narrow,  first 
thoracic  segment,  to  which  are  attached  a  pair  of  large  and 


Chap.  XL]  UNCONSCIOUS    COGNITION.  159 

powerful  arms  terminating  with  hooks,  with  which  it  is 
accustomed  to  seize  and  pierce  its  prey.  When  the  head 
together  with  this  first  thoracic  segment  was  excised,  the 
hody  of  the  Insect,  supported  on  its  four  remaining  legs, 
resisted  attempts  made  to  overturn  it,  and  at  the  same 
time  agitated  its  wings  and  wing-cases.  When,  after  this, 
the  head  was  detached  from  the  first  thoracic  segment,  the 
latter  single  and  isolated  body  segment  afterwards  showed 
signs  of  life  by  the  continuance  of  '  reflex  actions  '  of  a  pur- 
posive character  for  more  than  an  hour.  When  touched, 
it  moved  its  arms,  turning  them  towards  the  finger  of  the 
experimenter,  and  even  nipping  it  strongly. 

These  were  actions  of  much  the  same  kind  as  would 
have  been  exhibited  towards  a  Fly  or  other  prey,  if  the 
segment  had  formed  part  of  an  entire  Mantis.  In  such  a 
case,  the  movements  would,  doubtless,  have  been,  to  some 
extent,  consciously  instigated  through  the  Brain  of  the 
animal.  The  above-mentioned  experiment,  however,  shows 
conclusively  that  the  movements  of  the  arms  and  claws 
which  were  seen  when  the  thoracic  segment  was  severed 
from  the  head,  must  have  been  executed  through  the  inter- 
vention of  the  single  bilobed  ganglion,  together  with  the 
afferent  and  eff'erent  nerves  which  the  segment  contains. 

Dr.  Carpenter  says:*  "  If  the  head  of  a  Centipede  be 
cut  off  whilst  it  is  in  motion,  the  body  will  continue  to 
move  onwards  by  the  action  of  its  legs  ;  and  the  same  will 
take  place  in  the  separate  parts,  if  the  body  be  divided 
into  several  distinct  portions.  After  these  actions  have 
come  to  an  end,  they  may  be  excited  again  by  irritating 
any  part  of  the  nerve  centres,  or  the  cut  extremity  of  the 
nervous  cord.  The  body  is  mo^ed  forwards  by  the  regular 
and  successive  action  of  the  legs,  as  in  the  natural 
state ;  but  its  movements  are  always  forwards,  never 
*  "  Mental  Physiology,"  3rd  Edition,  p.  53. 


160  REFLEX    ACTION    AND 

backwards,  and  are  only  directed  to  one  side  when  the 
forward  movement  is  checked  by  an  interposed  obstacle.'* 

If  we  look  now  to  such  reflex  movements  as  are  com- 
monly manifested  by  one  of  the  higher  animals — a  Frog, 
for  instance — we  shall  meet  with  the  same  machine-like 
regularity  in  the  execution  of  motor  responses  to  ordinary 
stimuli,  the  same  semblance  of  an  intentional  effort  to 
accomplish  a  certain  end — even  when  the  animal  has  been 
deprived  of  its  Brain,  and  when  the  movements  are  there- 
fore as  involuntary  and  unconscious  as  those  of  the  thoracic 
segment  of  the  Mantis  above  referred  to. 

After  the  head  and  neck  of  a  narcotized  Frog  had  been 
removed,  Vulpian*  slightly  pinched  a  toe  of  one  of  the 
stretched-out  hind  limbs,  and  observed,  as  others  have 
done,  that  this  stimulus  was  quickly  followed  by  a  flexion 
of  all  the  se<.  m  'uts  of  the  limb  upon  one  another.  The 
same  result  constantly  followed  the  application  of  such  a 
stimulus,  and  as  Vulpian  points  out: — "It  is  not  an 
indefinite  reaction.  All  the  muscles  do  not  contract ;  for 
if  it  were  so,  there  would  be  forcible  extension  of  the  limb, 
as  in  strychnia  poisoning,  since  the  extensor  muscles  in 
the  frog   are   together  much  stronger  than    the    flexors. 

Here,    on   the  contrary,    a   certain    number   of 

muscles  only  contract,  while  the  others  remain  more  or 
less  inert.  There  is  a  contraction  of  muscles  combined  in 
such  a  manner  as  to  produce  a  particular  result,  and  the 
result  of  these  harmonized  contractions  is  to  withdraw  the 
limb  from  the  exciting  cause." 

A  much  stronger  excitation  applied  to  one  of  the  hinder 
paws  of  this  headless  Frog  will  lead  to  a  different  reaction, 
but  still  to  one  which  is  always  the  same  under  similar 
conditions.  We  no  longer  witness  a  movement  of  flexion 
in  the  limb  that  has  been  touched,  but  both  it  and  the 
*  "  La  Physiolgie  du  Systerae  Nerveux,"  p.  415. 


Chap.  XL]  UNCONSCIOUS    COGNITION.  IGl 

corresponding  limb  are  suddenly  extended  ;  and  *'  this 
movement  of  the  two  legs  is,"  as  Yulpian  says,  "  that 
which  is  most  appropriate,  either  to  repel  the  cause  of 
irritation  or  to  shoot  the  animal  forward,  and  so  remove 
it  from  the  influence  of  the  irritating  agent." 

Again,  if  the  skin  of  the  side  of  the  body  is  slightly 
pinched  in  a  headless  frog,  the  foot  of  the  hind  limb  on 
the  same  side  is  brought  up  so  as  to  endeavour  to  rub 
away  the  irritating  agent.  Here  also  we  have  a  complex 
movement  brought  about  by  many  muscles  definitely  com- 
bined and  adapted  to  obtain  a  certain  result.  But  the 
particular  movements  executed  always  vary  in  accordance 
with  the  site  of  irritation.  Thus,  a  pinch  at  the  posterior 
extremity  of  the  trunk,  evokes  wholly  different  movements 
from  those  just  described.  In  this  case,  according  to  the 
same  authority,  "  There  is  a  new  combination  of  muscular 
contractions,  by  means  of  which  the  feet  are  first  brought 
towards  the  point  irritated  and  there  pressed  together,  and 
then  the  limbs  are  suddenly  extended,  thus  giving  rise  to 
the  movement  most  suitable  for  repelling  the  cause  of 
irritation." 

In  addition  to  the  instances  already  cited  there  is  the 
celebrated  experiment  of  PflUger  still  to  be  mentioned,  in 
which  the  reflex  act  evoked  was  so  definite  and  purposive 
as  to  lead  him  to  claim  for  the  Spinal  Cord  a  kind  of  con- 
scious perceptive  power,  similar  to  that  which  physiologists 
generally  restrict  to  the  Brain.  He  placed  a  drop  of  acetic 
acid  on  the  upper  part  of  the  thigh  of  a  decapitated  Frog, 
and  the  segments  of  the  corresponding  limb  were  quickly 
flexed,  so  that  the  foot  was  made  to  rub  the  seat  of  irrita- 
tion. He  then  amputated  this  foot  of  the  headless  animal 
before  reapplyiiig  the  acetic  acid.  The  result  was  most 
remarkable.  The  maimed  animal  began  to  make  fresh 
efforts  to  rub  the  irritated  spot,  but  was  unable  to  reach 


162  UEFLEX    ACTION    AND 

it  now  that  the  foot  was  removed.  After  some  moments 
of  agitation,  as  if  the  brainless  creature  were  seeking  h  new 
means  of  accomplishing  its  end,  the  motor  stimulus  flowed 
out  in  a  different  direction,  causing  the  animal  to  bend 
the  limb  of  the  other  side  till  with  its  foot  it  succeeded 
in  rubbing  the  irritated  region. 

Thus,  as  Vulpian  says, — "  Each  spot  irritated  acts  as  a 
kind  of  spring  for  calling  into  play  a  mechanism  which 
varies  according  to  the  point  excited,  and  according  to  the 
intensity  of  the  excitation.  But  each  mechanism  that  is 
called  into  play  always  determines  a  tendency  to  remove 
the  region  irritated  from  the  irritating  cause.  The  efforts 
differ,  the  mechanism  differs  also,  but  both  are  always 
appropriate,  and,  as  it  were,  chosen." 

Multitudes  of  reflex  acts  having  the  same  general 
characteristics  are  quite  familiar  to  us  from  their  occur- 
rence in  the  higher  animals  and  in  man.  Of  these  it 
may  suflice  to  mention  the  closure  of  the  eyelid  before  aa 
approaching  body,  the  rapid  drawing  away  of  the  paw  or 
hand  from  injury,  the  throwing  out  of  the  arms  in  the  act 
of  falling,  the  movements  of  suction  and  deglutition 
following  impressions  on  mouth  and  throat,  together  with 
the  acts  of  vomiting,  coughing,  and  sneezing. 

It  will  have  been  seen  that  there  are  two  distinct 
sides  to  the  process  which  we  have  hitherto  been  consider- 
ing. We  have  to  take  into  account  what  occurs  on  the 
side  of  '  ingoing  currents,'  in  the  nervous  centre ;  and 
also  what  occurs  on  the  side  of  '  outgoing  currents.'  The 
latter  processes  are  the  distinct  sequences  of  the  former ; 
and  if  we  have  inverted  the  proper  order  of  description, 
and  have  referred  more  especially,  in  the  first  place,  to 
the  gradual  growth  of  the  power  of  performing  adaptive 
movements,  it  is  only  because  such  an  inversion  of  the 


Chap.  XL]  UNCONSCIOUS    COGNITION.  163 

natural  order  lias  commended  itself  from  the  peculiarities 
of  the  facts  to  be  explained. 

As  to  the  existence  or  nature  of  the  phenomena  which 
take  place  on  the  side  of  the  ingoing  current  in  lower 
animals  we  can  know  nothing  directly.  We  can  only 
infer  that  processes  of  great  importance  occur  on  this 
side,  because  of  the  increasingly  complex  and  purposive 
character  of  the  movements  which  higher  or  older  animals 
become  capable  of  manifesting. 

The  characters  of  the  movements,  therefore,  are  the 
objective  facts,  and  it  is  only  by  an  attentive  study  of 
them,  and  of  the  conditions  under  which  they  are  mani- 
fested, that  we  are  entitled  to  come  to  an  opinion  as  to 
the  occurrence  of  organic  discriminations  on  the  side  of 
the  ingoing  current — as  to  the  existence,  in  fact,  of  what 
we  can  only  term  *  unconscious  cognitions.* 


The  increase  in  the  number  and  variety  of  the  nervous 
impressions,  both  simultaneous  and  successive,  to  which 
Animal  Organisms  become  attuned  to  react,  takes  place 
at  a  comparatively  slow  rate.  The  addition  to  the  receptive 
powers  of  any  one  individual  are  only  slight,  and  it  is 
during  the  period  in  which  it  is  acquiring  these  powers 
that  the  corresponding  structural  changes  will  become 
more  and  more  perfected,  partly  in  the  form  of  new  or 
altered  nerve  cells,  and  partly  by  the  formation  of  inter- 
cellular processes  and  connecting  fibres.  And  owing  to 
the  fact  that  the  germ  or  egg  produced  by  an  organism 
always  tends  to  develop  into  a  form  similar  to  that  of  its 
parent  (similar  that  is  not  only  in  external  shape  but  in 
the  intimate  texture  and  arrangement  of  its  organs  and 
tissues),  the  successive  lineal  descendants  of  any  one  kind 
of  organism  may  in  effect  be  regarded  as  portions  of  the 


164  REFLEX    ACTION    AND 

same  organism,  gradually  developing  througli  successive 
generations  or  stages  of  one  life  history.* 

The  doctrine  of  '  Inherited  Acquisition,'  to  the  enuncia- 
tion and  development  of  which  we  are  so  largely  indehted 
to  Herbert  Spencer,  explains,  therefore,  how  it  is  that 
young  organisms,  only  just  arrived  at  maturity,  are  often 
better  adapted,  in  some  respects,  to  their  surroundings 
than  were  their  predecessors,  near  or  remote,  at  a  corre- 
sponding age.  Consequently,  if  during  their  lifetime 
again,  or  during  that  of  their  descendants,  some  further 
modes  of  impressibility  (with  corresponding  powers  of 
discrimination)  become  possible  either  in  old  or  in  new 
directions ;  and  if  simultaneously  there  arises  some  new 
or  altered  capacity  for  acting  in  response  to  these  new 
impressions,  it  will  not  be  difficult  for  the  reader  to 
understand  that  this  would  constitute  one  important  mode 
in  which  the  nervous  system  slowly  develops  and  becomes 
more  complex. 

Thus  it  is  that  habitual  or  often  recurring  stimuli  of 
new  kinds  are  presumed  to  be  constantly  leaving  their 
traces  in  the  plastic  tissues  of  lower  organisms,  and 
inducing  such  structui'al  modifications  in  them  as  tend  not 
only  to  make  the  recurrence  of  similar  impressions  more 
easy,  but  also  to  render  the  reception  and  recognition 
of  new  impressions  more  possible. 

Most  of  us  must  be  familiar  with  the  fact  that  by  the 
concentration  of  Attention  in  certain  directions,  aided  by 
voluntary  efforts,  we  are  capable  of  increasing  our  powers 
of  Discrimination  in  the  range  of  either  of  the  senses,  and 

*  The  many  influences  capable  of  accelerating  or  retarding  this 
kind  of  race  development  cannot  here  be  even  enumerated.  Suffice 
it  to  say  that  some  of  the  principal  of  them  have  been  described 
and  copiously  illustrated  by  Mr.  Darwin  in  his  works  on  "  The 
Origin  of  Species,"  and  on  "  Sexual  Selection." 


CuAP.  XI.  UNCONSCIOUS    COGNITION.  1C5 

that  each  new  acquirement  renders  possible  other  and 
more  refined  discriminations.  But  there  is  reason  to 
believe  that,  even  without  conscious  voluntary  efforts,  the 
same  kind  of  progress  (though  more  slowly)  is  capable  of 
being  brought  about  by  the  action  upon  the  organism  of 
all  the  varying  influences  by  which  it  is  surrounded. 

The  mode  by  which  mere  '  organic  discriminations  '  are 
rendered  possible  may  be,  in  part,  illustrated  by  reference 
to  the  building  up  of  the  links  between  conscious  dis- 
criminations and  actions  in  higher  organisms — such  as 
Cephalopods  and  Fishes. 

Particular  attention  must  be  called  to  the  fact  that 
each  new  impression  which  becomes  registered  is  not 
something  wholly  different  from  what  has  gone  before.  It 
is  rather  some  slight  modification  or  refinement  upon 
impressions  which  have  preceded  it,  and  just  as  it  takes 
iis  origin  in  similar  parts  of  the  body,  so  would  it  naturally 
proceed  to  those  same  regions  in  the  central  nervous 
system  to  which  preceding  impressions  of  like  kind 
had  been  transmitted.  The  determining  conditions  and 
route  by  which  the  impression  travels  could  scarcely  be 
different  in  the  case  of  some  new  visual  impressions,  for 
instance,  from  what  they  had  been  in  regard  to  all  previous 
visual  impressions.  Thus  the  physical  counterparts  of 
like  kinds  of  old  and  new  impressions  are  almost  neces- 
sarily brought  into  close  relation  with  one  another,  and 
with  the  same  sets  of  outgoing  nerve  fibres,  however 
these  latter  may  from  time  to  time  be  supplemented  and 
modified  in  their  combinations.  An  organic  continuity, 
in  fact,  is  supposed  to  lie  at  the  root  of  impressions  new 
and  old,  whereby  they  are  classed  at  the  same  time  that 
they  become  organized.  Intelligence  would  thus  be  sub- 
ject to  actual  '  growth '  in  more  senses  than  one.  The 
process  is  of  course  notably  more  complex  than  it  is  here 


166  REFLEX    ACTION    AND 

represented.     Some  of  the  essential  complications  of  the 
process  are,  however,  of  an  obvious  nature. 

It  is  not  only  that  impressions  of  touch  become  organi- 
cally related  to  other  impressions  of  the  same  kind,  that 
visual  impressions  become  classed  with  visual  impressions, 
and  so  on.  Unions  also  would  seem  to  spring  up  in  some 
less  explicable  way  between  central  nerve  units  of  different 
orders- — that  is,  between  contiguous  sensory  ganglia.  Thus 
if  in  the  experience  of  any  organism,  such  as  a  Cuttle- 
fish, visual  impressions  are  usually  quickly  followed  by 
tactile  impressions,  it  would  seem  for  various  reasons  to 
be  almost  certain  that  communicating  fibres  would  become 
developed  between  corresponding  portions  of  the  visual 
and  tactile  ganglia,  and  any  motor  response  that  might 
follow  would  thus  be  either  directly  or  indirectly  related 
to  foci  of  excitement  in  both  these  sense  centres.  In  the 
same  manner  the  odour  from  some  Cod-fish,  or  other 
object  of  prey,  may  reach  the  voracious  Shark  either  before 
the  object  is  seen  or  simultaneously,  and  these  two  im- 
pressions will,  in  a  very  large  number  of  cases,  be  followed 
by  certain  tactile  and  by  certain  gustatory  impressions. 
The  first  impressions  become  related  to  and  may  find  an 
outcome  in  the  production  of  movements  of  pursuit ;  while 
those  engendered  during  the  process  of  capture  (viz.,  of 
touch  and  taste  combined)  immediately  call  into  play  the 
complicated  simultaneous  and  successive  movements  of 
jaws,  throat,  oesophagus,  and  stomach,  which  form  part  of, 
or  are  accustomed  to  succeed,  the  act  of  swallowing. 

From  what  has  been  said  in  this  chapter,  it  may  be 
safely  concluded  that  as,  by  the  frequent  repetition  of  like 
Btimuli,  the  structural  connections  of  nerve  currents  (or 
the  precise  paths  of  ingoing  impressions  through  nerve 
centres  and  along  outgoing  nerve  fibres)  are  developed  and 


Chap.  XL]  UNCONSCIOUS    COGNITION.  167 

rendered  definite,  so  certain  appropriate  actions  will  follow 
certain  impressions  with  unfailing  regularity  and  precision. 
There  goes  on,  as  it  were,  an  organization  of  'Intelli- 
j^ence  '  primarily  of  the  organic  or  unconscious  kind,  which 
is  the  hidden  cause  of  the  purposive  character  displayed 
by  so  many  movements. 

We  say  that  the  process  is  primarily  of  the  organic 
or  unconscious  type,  because  one  may  witness  even 
in  Medusae  and  in  organisms  only  a  little  above  them 
actions  of  a  purposive  type  in  response  to  stimuli  acting 
upon  different  parts  of  their  bodies.  And  it  is  difficult 
to  believe  that  the  Neural  Developments  in  such  creatures, 
by  means  of  which  the  several  motions  follow  in  response 
to  the  several  stimuli,  can  have  been  brought  about  under 
the  influence  of  any  distinct  *  conscious  '  guidance.  We 
have  here,  doubtless,  to  do  with  '  organic  processes  '  only 
a  few  degrees  more  complex  than  those  which  may  take 
place  in  a  Sun-dew  or  other  '  Sensitive  Plant.' 

Organic  processes  of  the  same  kind  possibly  constitute 
the  basis  or  starting  point  for  all  subsequent  neural  de- 
velopments and  Mental  Acquisitions,  even  when  in  higher 
animals  such  processes  become  quickened,  in  some 
further  unknown  manner,  under  the  directive  influence  of 
Conscious  Efforts  of  gradually  increasing  distinctness. 


CHAPTER   XU. 

SENSATION,    IDEATION,    AND    PERCEPTIOTT. 

Neurology  may  be  advantageously  studied  by  beginning 
with  the  investigation  of  the  simplest  and  earliest  forms 
of  the  Nervous  System,  and  thence  proceeding  to  examine 
its  more  and  more  complex  types.  A  wholly  different 
order  is,  however,  compulsory,  in  regard  to  Psychology. 
Its  'subjective'  division  constitutes  for  each  of  us  the 
sphere  of  positive  knowledge  in  regard  to  this  subject  ; 
while  that  portion  of  *  objective  '  Psychology  having 
reference  to  the  mental  states  or  processes  of  our  fellow- 
men  has  the  next  greatest  amount  o±  certainty  for  us — 
since  the  human  faculty  of  Articulate  Speech  enables 
us  to  compare,  to  some  extent,  the  subjective  experiences 
of  other  men  with  our  own. 

Objective  Psychology,  so  far  as  it  relates  to  inferior 
forms  of  life,  is  merely  a  field  for  more  or  less  probable 
conjecture,  in  which  the  basis  of  certainty  diminishes  the 
further  we  depart  from  the  human  type.  Knowledge 
garnered  from  our  own  experiences  and  those  of  our 
fellow-creatures  affords,  as  it  were,  the  lamp  wherewith  we 
seek  to  illuminate  the  dark  places  of  animal  Psychology. 
Hence  it  is  necessary  for  us  in  the  first  place,  before 
attempting  to  consider  the  mental  processes  of  lower 
animals,  to  look  to  some  of  the  fundamental  facts  per- 
taining to  human  Psychology.      The  previous  consideration 


Chap.  XII.]  SENSATION,   IDEATION,  AND  PERCEPTION.  1G9 

of  '  Reflex  Action  and  Unconscious  Cognition,'  will  be 
fonnd  to  be  a  fully  justifiable  procedure,  and  it  was  equally 
desirable  that  its  consideration  should  have  been  prefaced 
by  an  enquiry  as  to  the  scope  of  *  Mind '  and  the  nature 
of  mental  phenomena. 

Descartes,  Leibnitz,  Spinosa,  and  other  philosophers 
have,  as  Sir  William  Hamilton  reminds  us,  been  led  to 
regard  "the  faculty  of  Cognition  as  the  fundamental 
power  of  mind  from  which  all  others  are  derivative  ;  " 
while  Condillac  and  his  school  attributed  this  rank  to 
Sensation  rather  than  to  Cognition,  and  similarly  derived 
all  other  mental  faculties  from  this  as  a  base  or  starting 
point. 

It  would  not  be  in  accordance  with  the  point  of  view 
of  Evolutionists  to  say  that  either  of  these  faculties  could 
generate  all  the  others.  If  we  grant  it  to  be  true,  that  one 
or  other  of  them — either  Cognition  or  Sensation — does, 
in  fact,  constitute  the  primary  manifestation  of  mental 
activity,  we  should  rather  say,  that  as  the  nervous  actions 
upon  which  the  mental  process  is  dependent  grow  more 
complex,  so  may  other  so-called  *  faculties '  of  mind  be 
gradually  engendered  as  related  phases  of  the  same  neu- 
rological activity,  and  marked  by  a  growing  tendency  to 
become  more  and  more  distinct  from  one  another. 

As  to  which  of  the  mental  modes  or  manifestations  is 
to  be  regarded  as  primary,  there  seems  to  us  to  be  little 
room  for  doubt.  Hamilton  truly  observes*  : — "  The 
faculty  of  knowledge  is  certainly  the  first  in  order,  inas- 
much as  it  is  the  conditio  sine  qua  non  of  the  others  ;  and 
we  are  able  to  conceive  a  being  possessed  of  the  power  of 
recognizing  existence,  and  yet  wholly  void  of  all  feeling  of 
pain  and  pleasure,  and  of  all  powers  of  desire  and  voli- 
tion.    On   the   other  hand,  we  are  wholly  unable  to  con- 

*  "  Lectures  on  Metaphysics."     Fifth  Edition,  vol.  i.,  p.  188. 


170  SF-NSATION,    IDEATION, 

ceive  a  being  possessed  of  feeling  and  desire,  and,  at  the 
same  time,  without  a  knowledge  of  any  object  upon  which 
his  affections  may  be  employed,  and  without  a  conscious- 
ness of  these  affections  themselves." 

Some  highly  significant  facts  have,  indeed,  already  been 
mentioned,  tending  to  show  that  mere  organic  discrimina- 
tions or  Cognitions  may  be  manifested  by  plants,  lower 
animals,  or  even  parts  of  animals  under  conditions  in 
which  it  is  not  warrantable  to  assume  the  co-existence  of 
anything  like  that  which  we  know  as  Consciousness  or 
Feeling.  We  have  seen  some  and  shall  find  more  reason 
for  believing  that  Feeling,  in  its  ordinary  acceptation,  is 
gradually  superadded,  in  higher  forms  of  animal  life,  as 
a  newly-begotten  accompaniment  of  nerve  actions  which 
hitherto,  in  lower  forms,  have  been  unendowed  with  any 
distinct  subjective  phasis.  At  first  we  may  have  the  exist- 
ence of  unconscious  impressions  and  mere  organic  dis- 
criminations ;  while  afterwards,  during  the  evolution  of 
the  animal  series,  and  consequently  of  nerve  centres,  we 
suppose  the  superaddition  to  some  nervous  actions  of  a 
more  and  more  definite  subjective  phasis,  answering  to 
lower  grades  of  what  each  of  us  knows  in  himself  only — 
during  processes  of  Sensation  or  Perception  more  especially. 

We  must  now  look,  from  our  human  point  of  view,  to 
what  is  included  under  these  latter  terms.  James  Mill 
says,* — "What  we  commonly  mean  when  we  use  the 
terms  Sensation  or  phenomena  of  Sensation,  are  the 
feelings  which  we  have  by  the  five  senses — Smell,  Taste, 
Hearing,  Touch,  and  S'ujht,  These  are  the  feelings  from 
which  we  derive  our  notions  of  what  we  denominate  the 
external  world — the  things  by  which  we  are  surrounded. 
.....  Wlien  we  smell  a  rose  there  is  a  particular 
feeling,  a  particular  consciousness,  distinct  from  all  others, 

*  "  Analysis  of  the  Human  Mind,"  1829,  vol.  i.  pp.  3  and  7, 


CiiAP.  XII.]  AND    PERCEPTION.  171 

which  we  mean  to  denote  when  we  call  it  the  smell  of  the 
rose.     In  like  manner  we  speak  of  the  smell  of  hay,  the 

smell  of  turpentine,   and  the  smell  of   a  fox 

We  can  distinguish  this  feeling,  this  consciousness,  the 
sensation  of  smell,  from  every  other  sensation.  Smell 
and  Sound  are  two  very  different  things ;  so  are  Smell 
and  Sight.  The  smell  of  a  rose  is  different  from  the 
colour  of  the  rose  ;  it  is  also  different  from  the  smooth- 
ness of  the  rose,  or  the  sensation  we  have  by  touching  the 

rose In  all  these  cases  what  we  speak  of  is  a 

point  of  consciousness,  a  thing  which  we  can  describe  no 
otherwise  than  by  calling  it  a  feeling;  a  part  of  that 
series,  that  succession,  that  flow  of  something,  on  account 
of  which  we  call  ourselves  living  or  sensitive  creatures. 

The  feelings,  however,  which  belong  to  the  live 

external  Senses  are  not  a  full  enumeration  of  the  feelings 
which  it  seems  proper  to  rank  under  the  head  of  Sensa- 
tions, and  which  must  be  considered  as  bearing  an 
important  part  in  those  complicated  phenomena  which  it 
is  our  principal  business  in  this  inquiry  to  separate  into 
their  principal  elements  and  explain.  Of  these  unnamed 
and  generally  unregarded  sensations,  two  principal  classes 
may  be  distinguished  : — first.  Those  which  accompany 
the  action  of  the  several  Muscles  of  the  body ;  and 
secondly,  those  which  have  their  place  in  the  Alimentary 
Canal  [and  other  internal  Viscera]." 

This  explanation  of  the  word  Sensation  is  clear  and 
leaves  room  for  no  uncertainty.  The  term  is  seen  to  be 
interchangeable  with  the  word  Feeling,  although  the  latter 
has  a  wider  signification  and  is  applicable  to  every  modi- 
fication of  Consciousness  whatsoever.  For  instance,  we 
are  said  to  feel  excited  or  depressed,  we  feel  fearful  or 
confident,  we  feel  joy  and  sorrow,  we  feel  love  and  hatred 
• — though  these  various    emotional  or   moral    states    are 


172  SENSATION,  IDEATION, 

sometimes  disiinguiished  from  our  more  primary  and 
simpler  feelings  by  calliag  them  *  Sentiments.' 

In  addition,  however,  to  the 'simple'  Sensations  experi- 
enced through  the  activity  of  the  organs  of  any  one  sense, 
we  are  capable  of  experiencing  clusters  of  simultaneous 
sensations  from  some  external  object.  It  is  in  part 
by  the  differences  existing  between  such  clusters  of  sen- 
sations that  we  are  able  to  distinguish  '  external  objects ' 
from  one  another.  Each  cluster  may  be  said  for  the 
present  to  answer  to  a  kind  of  *  complex '  Sensation,  and 
this  we  are  accustomed  to  denote  by  the  name  of  the 
corresponding  object.  A  qualification  of  this  statement 
will,  however,  subsequently  be  needed. 

Jamos  Mill  says, — "  The  name  rose  is  the  mark  of  a 
sensation  of  colour,  a  sensation  of  shape,  a  sensation  of 
touch,  a  sensation  of  smell,  all  in  conjunction.  The 
name  water  is  the  mark  of  a  sensation  of  colour,  a  sensa- 
tion of  touch,  a  sensation  of  taste,  and  other  sensations, 
regarded  not  separately  but  as  a  compound."  But  as  the 
same  writer  adds : — "  V\^e  not  only  give  names  to  clusters 
of  sensations,  but  to  clusters  of  clusters  ;  that  is,  to  a 
number  of  minor  clusters,  united  into  a  greater  cluster. 
Thus  we  give  the  name  '  wood  '  to  a  particular  cluster  of 
sensations, the  name  'canvas'  to  another,  the  name  'rope* 
to  another.  To  these  clusters,  and  many  others,  joined 
together  in  one  great  cluster,  we  give  the  name  'ship.'  To 
a  number  of  these  great  clusters  united  into  one  we  give 
the  name  'fleet'  and  so  on.  How  great  a  number  of  clusters 
are  united  in  the  term  'house'  ?  And  how  many  more  in 
the  term  'city'?" 

But  another  term  must  now  be  defined.  A  Sensation, 
whether  '  simple '  or  '  complex,'  which  has  once  been  ex- 
perienced is,  as  we  all  know,  apt  to  persist  or  to  be  revived 
in  memory.     On  this  subject,  again,  James  Mill  writes  : — • 


Chap.  XiL]  AND    PERCKPTJON.  173 

**  It  is  a  known  part  of  our  constitution  that  when  our 
sensations  cease,  by  the  absence  of  their  objects,  some- 
thing remains.  After  I  have  seen  the  sun,  and  by  shut- 
ting my  eyes  see  him  no  longer,  I  can  still  think  of  him. 
I  have  still  a  feeling,  the  consequence  of  the  sensation 
which — though  1  can  distinguish  it  from  the  sensation  and 
treat  of  it  as  not  the  sensation,  but  something  different 
from  the  sensation — is  yet  more  like  the  sensation  than 
anything  else  can  be ;  so  like  that  I  call  it  a  copy,  an 

image,    of    the    sensation Another   name   by 

which  we  denote  this  trace,  this  copy  of  the  sensation, 

which  remains  after  the  sensation  ceases,  is  Idea 

The  word  Idea  in  this  sense  will  express  no  theory  what- 
soever ;  nothing  but  the  bare  fact,  which  is  indisputable. 
We  have  two  classes  of  feelings  :  one,  that  which  exists 
when  the  object  of  sense  is  present ;  another,  that  which 
exists  after  the  object  of  sense  has  ceased  to  exist.  The 
one  class  of  feelings  I  call  Sensations,  the  other  class  of 

feelings  I  call  Ideas As  each  of  our  senses  has 

its  separate  class  of  sensations,  so  each  has  its  separate 
class  of  ideas.  We  have  ideas  of  sight,  ideas  of  touch, 
ideas  of  hearing,  ideas  of  taste,  and  ideas  of  smell.'* 
These  copies  of  sensations  may  recur  singly  or  in 
clusters,  so  that  they,  like  Sensations,  are  and  have  been 
long  classified  as  '  simple  '  and  '  complex.'  For  the  pro- 
cess of  recurrence  itself,  which  of  course  varies  much  in 
complexity,  James  Mill  proposed  the  term  Ideation. 

But  in  referring  to  the  sensations  derived  from,  and 
the  realization  of  the  nature  of,  an  '  external  object,'  we 
have  passed  beyond  the  range  of  '  Sensation  proper,'  and 
have  encroached  upon  what  is  commonly  considered  as 
*  Perception  proper.'  The  full  meaning  and  explanation  of 
this  statement  will  become  plain  if  we  briefly  consider  the 


174  SENSATION,  IDEATION, 

order  in  which  our  Sensations  and  Ideas  occur,  and  the 
modes  in  which  they  combine  with  one  another. 

With  respect  to  the  order  of  our  Sensations,  it  is  obvious 
enough  that,  to  a  considerable  extent,  they  occur  accord- 
ing to  the  order  estabhshed  among  what  we  call  the 
objects  and  phenomena  of  nature ;  and  that  these  are 
divisible  into  two  categories  : — (1)  the  synchronous  order, 
and  (2)  the  successive  order.  As  James  Mill  says  : — "  The 
synchronous  order,  or  order  of  simultaneous  existence,  is 
the  order  in  space  ;  the  successive  order,  or  order  of 
antecedent  and  consequent  existence,  is  the  order  in  time. 
Thus  the  various  objects  in  my  room,  the  chairs,  the 
tables,  the  books,  have  the  synchronous  order,  or  order  in 
space.  The  falling  of  the  spark  and  the  explosion  of 
gunpowder  have  the  successive  order,  or  order  in  time." 

We  habitually  receive,  therefore,  synchronous  Sensations 
from  external  objects  co- existing  in  space,  and  w^e  as 
habitually  receive  trains  of  successive  Sensations  follow- 
ing one  another  in  time.  And  as  Ideas  are  merely  weak 
copies  or  revivals  of  Sensations,  it  is  only  natural  to 
expect  that  they  would,  as  they  do,  derive  their  order  in 
the  main  from  that  of  our  sensations.  On  this  head 
Herbert  Spencer*  remarks, — *'  the  persistence  of  the  con- 
nection between  states  of  consciousness  is  proportionate 
to  the  persistence  of  the  connection  between  the  agencies 
to  which  they  answer.  The  relations  between  external 
objects,  attributes,  acts,  are  of  all  grades  from  the 
necessary  to  the  fortuitous.  The  relations  between  the 
answering  states  of  consciousness  must  similarly  be  of 
all  grades  from  the  necessary  to  the  fortuitous." 

Now  it  so  happens  that  *'  of  the  objects  from  which  we 
derive  the  greatest  part  of  our  sensations,  most  of  those 
which  are  observed  syn chronically  are  frequently  observed 
*  "Principles  of  Psychology,"  vol.  i.  p.  448. 


Chap.  X!T.]  AND    PERCEPTION.  175 

Byiicbroiiically ;  most  of  those  which  are  observed  succes- 
sively are  frequently  observed  successively."  *  But  the 
effects  of  such  repetitions  of  Sensations,  '  associated  '  by 
their  occurrence  either  "  precisely  at  the  same  instant  of 
time  or  in  the  contiguous  successive  instants,"  and 
whether  referring  to  the  same  object  or  to  different  ob- 
jects, w^ere  clearly  enunciated  nearly  a  century  and  a  half 
ago  by  Hartley  in  his  celebrated  '  Doctrine  of  Associa- 
tion.'! He  then  laid  down  the  following  important  law 
of  Mind: — ''Any  S (insect ions,  A,B,C,  dc,  by  being  asso- 
ciated with  one  another  a  sufficient  Number  of  Times,  get 
such  a  Poiver  over  the  corresponding  Ideas,  a,  b,  c,  c&c, 
that  any  one  of  the  Sensations  A,  when  impressed  alone, 
shall  be  able  to  excite  in  the  Mind  b,  c,  d;c.,  the  Ideas  of 
the  rest."  Muscular  Motions  were  also  shown  by 
Hartley!  to  exhibit  a  similar  tendency  to  cohere  with 
Sensations  and  Ideas,  and  "  the  whole  doctrine  of  asso- 
ciation "  was  comprised  by  him  in  a  '  theorem  '  to  that 
effect,  almost  precisely  similar  to  what  has  been  re-affirmed 
and  fully  illustrated  in  our  own  time,  by  Alexander  Bain, 
as  '  The  Law  of  Contiguity.' 

Hartley,  moreover,  showed  that  "  Simple  Ideas  will  run 
into  complex  ones,  by  means  of  Association  ;  "  and  on  this 
head  James  Mill  says  : — "  Ideas,  also,  which  have  been  so 
often  conjoined  that  whenever  one  exists  in  the  mind  the 
other  exists  along  with  it,  seem  to  run  into  one  another, 
to  coalesce,  as  it  v/ere,  and  out  of  many  to  form  one  idea, 
which  idea,  however,  in  reality  complex,  appears  to  be  no 
less  simple  than  any  one  of  those  of  which  it  is  com- 
pounded. .  .  .  The  word  'gold,'  for  example,  or  the  word 
*iron,'  appears  to  express  as  simple  an  idea  as  the  word 

*  James  Mill,  loc.  cit.,  p.  55. 

t  "  Oltservations  on  Man."     Sixth  Edition,  1834,  p.  41. 

J  Loc.  cit.,  p.  65. 


176  SENSATION, 

*  colour*  or  the  word  'sound.'  Yet  it  is  immediately  seen 
that  the  idea  of  each  of  those  metals  is  made  up  of  the 
separate  ideas  of  several  sensations :  colour,  hardness, 
extension,  weight.  Those  ideas,  however,  present  them- 
selves in  such  intimate  union,  that  they  are  constantly 
spoken  of  as  one,  not  many.  We  say,  our  idea  of  iron, 
our  idea  of  gold  ;  and  it  is  only  with  an  effort  that  reflect- 
ing men  perform  the  decomposition." 

Ideas  fuse  themselves  in  this  manner  into  clusters,  or 
complex  ideas,  because,  being  only  repetitions  or  weak 
copies  of  sensations,  they  are  reproduced  in  the  same  order 
as  the  sensations.  And  the  Sensations  in  question  habitu- 
ally occur  in  clusters  because  the  *  external  objects  '  to 
which  they  correspond  usually  impress  the  organism  sim- 
ultaneously through  different  senses.  Thus  it  happens, 
according  to  the  law  above  cited  from  Hartley,  that  when 
any  one  constituent  of  a  natural  cluster  of  sensations 
comes  within  the  range  of  the  corresponding  sense  organs 
of  an  animal,  the  other  possible  impressions  composing  the 
cluster  (and  representing  the  organism's  knowledge  of  the 
external  object)  become  simultaneously  nascent  in  memory, 
so  that  the  object  is  perceived  or  recognized.  If  in  a  dai'k 
room  my  hand  comes  upon  an  orange  or  upon  a  book, 
either  of  these  sensations  of  touch  will  immediately  fuse 
with  nascent  ideas  of  other  possible  sensations  from  the 
same  object  (whichever  it  may  be)  so  that  this  object  is 
perceived  as  a  present  external  reality.  This,  then,  is  the 
nature  of  the  process  known  as  Perception  :  in  which  we 
have  a  present   sensation  linking  itself  indissolubly  by 

*  association '  with  a  complex  idea  derived  from  our  •  past 
experiences  with  similar  objects.  It  is  not,  as  James  Mill 
implies,  the  appreciation  of  a  mere  '  cluster  of  sensations.' 

Thus  it  happens  that  an  object  is  recognized  imme- 
diately or  intuitively,  not  so  much  by  the  mere  single  or 


CaA?.  XIL]  AND    PERCEPT  [ON.  177 

double  present  impression,  as  by  the  blending  of  this 
with  more  or  less  fully  revived  memories  of  other  impres- 
sions which  have  at  various  times  been  associated  with 
the  same  object.  Truly  enough,  as  Bain  says  : — "  When 
we  see,  hear,  touch,  or  move,  what  comes  before  us  is 
really  contributed  more  by  the  mind  itself  than  by  the 
present  object." 

Different  Perceptions,  as  the  reader  will  easily  under- 
stand, vary  immensely  in  the  complexity  of  their  contents. 
This  quality  is  always  strictly  dependent  upon  the  wealth 
of  antecedent  experiences  in  relation  to  any  object  present 
to  sense,  both  in  the  individual  itself  and  in  the  race 
from  which  it  has  been  derived.  The  natural  simpli- 
city or  complexity  of  the  object  perceived  is  also,  of 
course,  of  great  importance.  The  possible  impressions 
comprised  in  the  perception  of  a  bar  of  '  iron '  are 
naturally  few  in  comparison  with  those  which  may  be 
included  under  the  perception  of  a  '  house.'  Still,  the 
same  object  may  in  different  men  excite  perceptions  of 
quite  a  different  nature.  A  savage  who  has  never  seen 
gunpowder  before  would,  for  instance,  have  a  set  of 
notions  called  up  by  the  sight  of  it,  which  would  not  at 
all  correspond  with  those  of  an  educated  European  who 
well  knew  its  composition  and  properties.  To  the  one  it 
would  appear  as  a  black  powder,  and  he  would  perceive  it 
more  or  less  simply  as  such.  The  perception  of  the  same 
substance  by  the  European,  however,  would  be  much 
more  complex,  containing  more  or  less  fully  revived  ideas 
as  to  its  nature,  together  with  half-i: ascent  memories  of 
the  various  kinds  of  effects  which  it  is  capable  of  pro- 
ducing by  explosion. 

A  neuro-physiological  interpretation  of  Perception  will 
here  serve  more  fully  to  elucidate  this  important  process, 
and  show  its    harmony  with  what   has   previously  been 


178  SENSATION,    IDEATION, 

said  in   regard  to  the  functional  activity  of  the  Nervous 
System. 

It  is  only  in  comparatively  low  organisms,  or  in  some  of 
the  nerve  actions  of  higher  organisms,  that  ingoing  im- 
pressions would  impinge  upon  a  more  or  less  isolated 
group  of  nerve-cells,  and  he  thence  transmitted  to  other 
cells  and  along  outgoing  fibres  to  groups  of  muscles.  This 
is  what  occurs  in  the  simplest  kinds  of  'reflex  action.' 
But  just  as  complications  seem  almost  inevitably  to  spring 
up  on  the  outgoing  side,  in  the  form  of  new  nervous 
connections  between  groups  of  motor  cells  (serving  to  ren- 
der possible  those  complex  simultaneous  and  successive 
movements  seen  in  the  more  elaborate  '  reflex  actions  '  of 
the  Frog  and  other  animals),  so  in  the  manner  briefly 
indicated  in  the  last  chapter,  will  analogous  structural 
complications  spring  up  in  the  highest  nerve  centres  on 
the  side  of  ingoing  currents.  Here  connections  become 
established  between  the  organic  mechanisms  concerned 
with  the  passage  of  simultaneous  or  successive  impressions, 
excited  by  objects  in  the  outside  world. 

Thus,  in  relation  with  the  most  familiar  '  external  ob- 
jects,' a  connected  internal  symbolic  register  of  their  attri- 
butes and  relations  is  gradually  established  in  the  Brain. 
There  is  an  opening  up,  in  some  habitual  but  imperfectly 
understood  manner,  of  a  series  of  interconnecting  channels 
or  fibres  between  particular  cells  in  each  of  the  impressed 
Sensory  Centres  and  all  the  others.  This  would  always 
occur  in  accordance  with  a  fixed  plan  (p.  166). 

When,  therefore,  an  external  object  is  '  perceived '  by 
any  animal  having  developed  sense-organs,  an  impression 
upon  one  or  more  of  its  sense-centres  suffices  to  rouse 
into  simultaneous  conjoint  activity  not  only  these  but  also 
other  centres  in  parts  of  the   brain  which  have  previously 


Chap.  XII.]  AND    PERCEPTION.  179 

been  called  into  action  when  an  object  of  the  same  kind 
had  been  presented.  It  is,  therefore,  by  the  simultaneous 
consciousness  and  fusion,  as  it  were,  of  the  sa])jecLive 
sides  of  various  new  and  old  impressions  that  a  present 
object  is  'perceived,'  or  recognized.  It  could  only  be 
by  the  previous  establishment  of  structural  communica- 
tions between  the  several  related  sensory  cells,  that  the 
excitation  of  those  of  any  one  order  would  suffice  to  revive 
more  or  less  strongly  in  other  groups  just  such  molecular 
changes  as  like  objects  had  on  previous  occasions  excited. 
And  it  may  be  easily  understood  that  the  molecular 
movements  initiated  by  any  one  or  two  ingoing  sense 
impressions,  may  start  from  such  groups  of  cells  and 
thence  flow  over  into  all  communicating  channels  be- 
tween them  and  the  cells  of  other  related  groups — ^just 
as  outpoured  water  from  some  overfull  lake  or  reservoir 
would  flow  easily  through  any  set  of  connected  channels 
which  might  have  become  established  around  it.  The 
more  definite  the  nervous  paths,  and  the  more  frequently 
they  have  been  traversed  by  stimuli,  the  easier  will  it  be 
for  molecular  movements  (as  it  would  be  for  water,  in  the 
illustration  given)  to  flow  along  such  channels  when  the 
next  occasion  arises. 

Some  such  process  aa  is  above  indicated  would  seem 
to  correspond  physically  with  what  is  known  as  an  act 
of  Perception.  As  the  writer  has  elsewhere*  pointed 
out,  one  of  the  principal  features  of  such  an  act  is  that  it 
tends  to  associate,  as  it  were,  into  one  state  of  conscious- 
ness much  of  the  knowledge  which  has  been  derived  at  dif- 
ferent times  and  in  different  ways  concerning  any  particular 
external  object.  When  impressions  from  such  an  object  are 
made  upon  any  sensory  nuclei,  they  strike  first  upon  the 
corresponding  '  perceptive  centres  '  in  the  cerebral  hemi- 
•  "  The  Physiology  of  Thinking."—"  Brit.  Med.  Journ  ,"  May,  1869. 


ISO  SENSATION,    IDEATION, 

spheres  and  thence  immediately  radiate  to  other  percep- 
tive centres,  there  to  rouse  the  activities  of  functionally 
related  cells.  This  process  takes  place  with  such  rapidity 
that  the  several  excitations  are  practically  simultaneous, 
and  the  combined  effects  are  fused  into  one  single  act 
of  Perception.  Thus,  I  see  an  orange  at  a  distance  ; 
this,  as  an  object  of  visual  sense,  is  simply  a  rounded 
yellow  area  ;  but  past  experience  has  led  me  to  know  what 
are  the  tactile  and  muscular  sensations  usually  associated 
with  the  sight  impressions — how  it  is  really  a  spherical 
body,  with  a  somewhat  rough  surface.  Then  I  have 
learned,  also,  that  these  impressions  are  usually  associated 
with  a  certain  odour,  with  a  certain  taste,  a  degree  of 
succulence,  and  certain  internal  visual  characters,  includ- 
ing a  divisibility  into  segments  and  the  possible  presence 
of  seeds  within.  A  combination  of  any  of  these,  or  of  a 
host  of  other  revivable  impressions,  may  go  to  constitute 
my  'perception'  of  an  orange,  and  may  flash  into  conscious- 
ness more  or  less  simultaneously,  on  the  presentation  of 
the  object  to  the  visual  sense. 

If  we  now  turn  our  attention  to  another  aspect  of  the 
question,  and  look  to  the  notable  differences  existing 
between  different  kinds  of  Sensations,  it  will  gradually 
be  made  plain  that  these  are  marked  off  from  simple 
and  complex  Perceptions  by  differences  of  degree  rather 
than  of  kind,  and  also  that  Emotion  and  Intellect  are,  in 
their  rudimentary  phases,  alike  inseparable  even  from 
simple  Sensations. 

Professor  Bain  says, — "  Some  sensations  are  mere 
pleasures  or  pains,  and  little  else  ;  such  are  the  feelings  of 
organic  life,  and  the  sweet  and  bitter  tastes  and  odours. 
Others  stretch  away  into  the  regions  of  pure  intellect,  and 
are   nothing  as  regards   enjoyment  or  suffering,   as,  for 


Chap.  XIT.]  AND    PERCEPTION.  181 

example,  a  great  number  of  those  of  the  three  higher 
senses."  This  difference  is  more  fully  explained  when  he 
says,  ''If  we  examine  the  sensations  of  organic  life,  Taste, 
and  Smell,  we  shall  find  that,  as  regards  pleasure  and  pain, 
or  in  the  emotional  point  of  view,  they  are  of  great  conse- 
quence ;  but  that  they  contribute  very  little  of  the  per- 
manent forms  and  imagery  employed  in  our  intellectual 
processes.  This  last  function  is  mainly  served  by  Touch, 
Hearing,  and  Sight,  which  may  therefore  be  called  the  Intel- 
lectual Senses  by  pre-eminence.  They  are  not,  however, 
thereby  prevented  from  serving  the  other  function  also,  or 
from  entering  into  the  pleasures  or  pains  of  our  emotional 
life." 

In  what  is  above  said  the  important  fact  is  implied  that  to 
every  Sensation  there  are  two  sides,  an  'emotional'  and  an 
'intellectual,'  and  that  in  some  sense-impressions  the  one, 
and  in  some  the  other,  predominates.  'J'his,  in  slightly 
different  terms  (viz.,  the  inverse  proportion  of  Sensation 
and  Perception),  has  been  strongly  insisted  upon  by  Sir 
William  Hamilton.  In  illustration  the  following  passage 
may  be  placed  before  the  reader.  He  says  : — "  If  w^e  take 
a  survey  of  the  Senses,  we  shall  find,  that  exactly  in 
proportion  as  each  affords  an  idiopathic  sensation  more 
or  less  capable  of  being  carried  to  an  extreme  either  of 
pleasure  or  of  pain,  does  it  afford,  but  in  an  inverse  ratio, 
the  condition  of  an  objective  perception  more  or  less 
distinct.  In  the  senses  of  Sight  and  Hearing,  as  contrasted 
with  those  of  Taste  and  Smell,  the  counter-propositions  are 
precise  and  manifest ;  and  precisely  as  in  animals  these 
latter  senses  gain  in  their  objective  character  as  means  of 
knowledge,  do  they  lose  in  their  subjective  character  as 
sources  of  pleasurable  or  painful  sensations.  To  a  Dog, 
for  instance,  in  whom  the  sense  of  Smell  is  so  acute,  all 
odours  seem,  in  themselves,  to  be  indifferent.  In  Touch 
9 


182  SENSATION,    IDEATION, 

or  Feeling  the  same  analogy  holds  good,  and  within  itself; 
for  in  this  case,  where  the  sense  is  diifused  throughout 
the  body,  the  subjective  and  the  objective  vary  in  their 
proportions  at  different  parts.  The  parts  most  subjectively 
sensible,  those  chiefly  susceptible  of  pain  and  pleasure, 
furnish  precisely  the  obtusest  organs  of  touch  ;  and  the 
acutest  organs  of  touch  do  not  possess,  if  ever  even  that, 
more  than  an  average  amount  of  subjective  sensibility." 

Sensation  is,  in  fact,  a  complex  rather  than  a  simple 
mental  process.  It  is  invariably  compounded  of  Cogni- 
tion and  Feeling. 

That  there  is  a  discriminative  or 'intellectual'  side  to  even 
the  most  subjective  of  our  Sensations  is  fully  admitted 
by  Hamilton  and  others.  Any  Sensation,  however  simple, 
can  only  be  recognized  as  such — can  only  become  an 
element  of  our  Consciousness,  (<x)  by  the  simultaneous 
memory  or  revival  of  some  past  impressions,  (b)  by  the 
intuitive  recognition  of  their  likeness  or  unlikeness  to  the 
present  impression,  and  (c)  by  the  similar  recognition  that 
this  is  felt  as  in  a  certain  place.  This  holds  good  even  for 
Touches  and  Tastes  which  are  habitually  referred  to 
some  part  of  that  inner  circle  of  the  Non-Ego,  repre- 
sented by  the  organism's  own  body.  And  in  reference  to 
such  Odours,  Sounds,  and  Sights  as  are  referred  to  the 
outside  world  beyond  the  organism,  it  becomes  plainly 
impossible  to  attempt  to  preserve  any  real  distinction  ho- 
tween  Sensations  and  Perceptions — since  precisely  the  same 
mental  processes  are  involved  in  both.  Thus,  according  to 
Sir  William  Hamilton,  Perception  also  is  *'  an  Assertory 
Judgment,  that  within  the  sphere  of  sense  an  object 
exists,  and  exists  thus  or  tlms  conditioned.^'  The  number 
of  the  '  conditions'  may,  of  course,  vary  greatly,  but  without 
altering  the  real  nature  of  the  process.  Indeed  he  subse- 
quently says,  "It is  manifestly  impossible  to  discriminate, 


Chap.  XII.]  AND    PERCEPTION.  183 

with  any  rigour,  Sense  from  Intellect;  "  and  after  calling 
attention  to  the  similar  opinion  held  by  Aristotle,  adds 
these  words,  "  Sensitive  apprehension  is,  in  truth,  only  the 
recognition  by  Intelligence  of  the  phenomena  presented  in 
or  through  its  organs." 

It  seems  plain,  therefore,  that  a  gradual  transition  may 
be  traced  between  simple  Sensations  and  the  most  elabo- 
rate Perceptions  ;  that  there  is  a  difference  in  degree, 
rather  than  in  kind,  between  these  two  processes  ;  and 
that  James  Mill,  in  his  "  Analysis  of  the  Human  Mind," 
was  not  without  justification  in  making  no  use  of  the  latter 
term,  and  in  speaking  merely  of  'simple  '  and  of  'complex' 
Sensations.  Moreover,  it  must  be  steadfastly  borne  in 
mind,  that  in  every  complex  Sensation  (or  Perception)  of 
an  external  object,  there  occurs  an  embodied  cluster  of 
judgments  and  inferences,  similar  in  kind  to  those  which 
compose  the  basis  of  all  Intellectual  Action.  Thus  the 
notion  that  an  intellectual  element  enters  into  the  very 
groundwork  of  all  Sensations  is  so  well  founded  as  to  make 
it  not  at  all  surprising  that  such  an  opinion  should  have 
been  held  alike  by  ancient  and  by  more  modern  philosophers. 

It  will  be  probably  far  less  difficult  for  the  general  reader 
to  acknowledge  the  fact  of  the  close  genetic  relations 
existing  between  Sensations  and  those  complex  states  of 
feeling  known  as  Emotions,  than  for  him  to  recognize  the 
relationship,  above  pointed  out,  between  Sense  and  Intel- 
lect. This  is  natural  enough,  because  those  who  have  not 
reflected  or  read  much  on  these  subjects,  are  apt  not 
adequately  to  appreciate  the  importance  of  the  Intellectual 
element  in  all  Sensations,  though  they  may  have  little 
difficulty  in  recognizing  that  Sensation  and  Emotion  are 
merely  different  kinds  of  Feeling.  It  will  not,  therefore, 
at  present,  be  necessary  to  dwell  long  upon  this  latter 
aspect  of  the  problem  as  to  the  genesis  of  Mind. 


184  SENSATION,    IDEATION, 

We  may  safely  assume  it  to  be  admitted,  as  a  general 
truth,  that  Emotions  of  various  kinds  gradually  mani- 
fest themselves  and  gain  in  strength,  as  the  sensorial 
endowments  of  animals,  and  their  relational  correspondence 
with  their  environment,  increase  in  definiteness  and  com- 
plexity. '  Pleasures'  and  *  pains'  soon  begin  to  be  realized 
as  direct  results  of  their  various  movements  and  sensorial 
activities,  and  from  the  traces  of  these  which  survive  in 
the  form  of  nascent  and  clustered  memories  of  many 
related  sensations,  those  numerous,  vague,  but  all-powerful 
modes  of  Feeling,  commonly  known  as  Emotions,  take 
their  origin,  and  often  seem  to  increase  in  strength  as 
the  wealth  of  associations  from  which  they  are  derived 
becomes  organized  and  widened  in  successive  genera- 
tions of  animals.  The  revival  of  such  vague  clustered 
memories  of  '  pleasures  *  or  '  pains  '  usually  follows  as  a 
direct  result  of  some  Perception.  An  impression  made 
upon  some  organ  of  sense  may  thence  reverberate  through 
the  brain  so  as  to  produce  a  Perception  of  the  correspond- 
ing object,  and  may  simultaneously  evoke  some  distinctly 
related  Emotion.* 

This  double  or  two-sided  nature  of  Sensation,  and  the 
necessary  development  from  it  of  the  germs  of  Intellect 
on  the  one  side,  and  of  Emotion  on  the  other,  as  from  a 
common  root,  is  a  fact  of  the  greatest  interest  from  a 
physiological  as  well  as  from  a  philosophical  point  of  view. 
We  must  perforce  admit  that  every  kind  of  Sensation  hns 
two  distinct  though  closely  related  sides,  the  one  of  which, 
as  mere  Feeling,  reveals  the  mode  of  affection  of  the  E(/(-  ; 
while  the  other,  as  Discrimination  or  Cognition,  reveals 
the  relations  and  qualities  of  what  we   call  the  Non-Ego. 

*  On  the  subject  of  the  genesis  of  Ere.otioTi,  the  reaaer  may 
consult  a  chapter  in  Herbert  Spencer's  "  Principles  of  Psy- 
chology," vol.  i.  pp.  481-494 


C:iAP.  XII.]  AND    PERCEPTION.  185 

These  two  compoDeiits  exist  in  every  Sensation,  though, 
as  Sir  William  Hamilton  contends,  in  an  inverse  ratio. 
The  formula  of  the  one  is  I  feel,  the  formula  of  the  other 
/  know.  The  one  is  represented  by  what  has  been  termed 
*  Sensation  proper,'  and,  in  its  higher  developments,  by 
Emotions,  and  Moral  Sentiments ;  the  other  by  *  Percep- 
tion proper,'  and,  in  its  higher  developments,  by  Judg- 
ment, Imagination,  Conception,  Reasoning,  or  the  more 
purely  Intellectual  Processes. 

There  is,  indeed,  a  third  aspect  of  Sensation  or  Percep- 
tion, which  has  not  yet  been  mentioned,  though  it  seems 
to  be  one  of  great  importance  in  helping  to  determine  the 
Development  of  Nervous  Structures,  and  the  correlative 
increasing  complexity  of  Mental  Phenomena.  This  is  to 
be  found  in  that  exercise  of  Volition  or  Will  which  enters 
into  every  Perception  under  the  form  of  Attention.  Nor 
must  it  be  here  forgotten  that  in  still  another  way  are 
Sensations  related  to  Volitions.  The  pleasures  and  pains 
of  Sense,  either  actually  present  or  represented  in  Idea, 
seem  unquestionably  to  constitute  the  subjective  sides  of 
those  neural  processes  which  most  frequently  issue  in  the 
so-called  Volitional  Movements.  But  this  subject  will 
be  more  fully  considered  in  a  later  chapter. 

It  is  of  great  importance,  however,  here  to  note  that 
Intelligence,  Sensation,  Emotion,  and  Volition  are  mental 
processes,  the  primary  stages  of  which  are  dependent 
upon,  and  inseparably  connected  with,  different  modes  or 
aspects  of  the  functional  activity  of  the  Perceptive  Centres; 
and  that  this  conclusion  at  which  we  have  arrived  is  one 
which  will  be  found  to  be  quite  harmonious  with  the  dicta 
of  philosophers  in  regard  to  human  Psychology.  Thus 
Sir  William  Hamilton  says*: — "  In  every,  the  simplest, 
modifications  of  Mind,  Knowledge,  Eeeling,  and  Desire  or 
*  "  Lectures  oa  Metaphysics,"  vol.  i.  p.  188. 


186  SENSATION,  IDEATION, 

Will  go  to  constitute  the  mental  state ;  and  it  is  only  by 
scientific  abstraction  that  we  are  able  to  analyze  the  state 
into  elements  which  are  never  really  existent  but  in 
mutual  combination.  These  elements  are  found,  indeed, 
in  very  various  proportions  in  different  states — sometimes 
one  preponderates  and  sometimes  another ;  but  there  is 
no  state  in  which  they  are  not  all  co-existent."  Similar 
views  have  been  even  more  prominently  urged  by  Herbert 
Spencer,  and  they  are,  moreover,  fully  in  accordance  with 
Lis  general  notion  that  "  the  highest  forms  of  psychical 
activity  arise  little  by  little  out  of  the  lowest,  and  cannot 
be  definitely  separated  from  them.'*  * 

But  why,  it  may  be  asked,  should  progress  be  observed 
in  the  development  of  the  Perceptive  Powers  and  all  that 
this  includes,  as  we  pass  from  lower  to  higher  animals  ? 
and  what  evidence  have  we  that  the  acquirements  and  sus- 
ceptibilities of  one  generation  of  animals  are  handed  down 
to  the  next,  to  be  by  them  improved  upon  and  transmitted 
in  turn  ?  These  all-important  questions  now  need  our 
brief  but  earnest  attention. 

Life  is  aptly  described  in  general  terms  by  tierbert 
Spencer,  as  ''  the  continuous  adaptation  of  internal  to 
external  conditions,''^  Nerve  tissues  and  organs  are,  as 
we  have  seen  reason  to  believe,  at  once  the  result  of  this 
correspondence,  and  the  means  whereby  it  becomes  organ- 
ically registered.  And  as  mental  phenomena  are  held  to 
result  from  the  actions  of  this  registering  mechanism,  they 
must  necessarily  show  something  of  that  continuity  which 
exists  in  the  mechanism  itself.  As  the  degree  of  corre- 
spondence between  the  organism  and  its  surroundings 
increases,  the  sum  total  of  mental  phenomena  must  be 

*  See  "  Principles  of  Physiology,"  vol.  ii.  pp.  512-516. 


Chap.  XII.]  AND    PERCEPTION.  187 

increased  and  modified  in  a  manner  related  to  tlie  new 
developments  and  modifications  taking  place  in  the  regis- 
tering mechanism  itself. 

There  must,  therefore,  from  the  very  nature  of  things, 
always  exist  an  organized  continuity  in  the  mental  phe- 
nomena possible  to  organisms,  quite  independent  of  the 
nature  of  the  phenomena  themselves — that  is,  whether 
they  be  high  or  low,  complex  or  simple.  The  mental 
processes,  moreover,  whose  nervous  substrata  are  fully 
organized,  would,  in  accordance  with  this  view  and  with 
the  doctrine  of  hereditary  transmission,  always  represent 
what  is  most  permanent  or  habitual  in  the  experiences 
of  the  race.  Mind  thus  truly  becomes,  and  cannot  be 
other  than,  a  faithful  reflex  of  the  vital  relations  and 
activities  of  the  organism. 

The  doctrine  of  '  Inherited  Acquisition '  is  not  only 
widely  applicable  in  explanation  of  the  genesis  of  Mind  in 
the  animal  series ;  it  suffices,  moreover,  to  reconcile  the 
adverse  doctrines  of  the  '  Transcendental '  and  the  '  Em- 
pirical '  schools  of  Philosophy.  It  shows  that  the  former 
were  right  in  a  certain  sense,  in  contending  for  the  exist- 
ence of  '  innate  ideas  ' ;  though,  looked  at  from  a  larger 
point  of  view,  it  strongly  tends  to  confirm  the  views  of  the 
experiential  school  of  philosophy.  All  knowledge  comes 
from  '  experience  ' — not  from  that  of  the  individual,  except 
to  a  comparatively  small  extent,  but  rather  from  that  of  the 
race.  This  in  the  main  is  transmitted,  by  the  inheritance 
of  the  ancestral  type  of  nervous  mechanism,  which,  in  pre- 
ceding countless  generations,  has  been  slowly  attuned  to  cer- 
tain modes  of  action,  and  needs  only  the  incidence  of  certain 
impressions  to  set  it  going.  This  is  now  no  mere  theory. 
In  so  far  as  it  concerns  Perceptions  and  Instinctive  Acts, 
the  doctrine  may  be  regarded  as  substantially  proved — 
the  highly  interesting   observations  and  experiments  of 


188  SENSATION,    IDEATION, 

Douglas  A.  Spalding*  in  relation  to  the  untaught  Percep- 
tions, Emotions,  and  Motor  Powers  of  Birds,  having  sup- 
plied a  final  confirmation  which  was  needed. 

Many  of  Spalding's  observations  were  made  upon  young 
Chickens,  some  of  which  were  carefully  hooded  as  they 
emerged  from  the  egg,  and  for  two  or  three  days  thereafter, 
so  as  not  to  permit  the  incidence  of  any  Sight  impressions. 
The  young  Birds  being  then  placed  on  a  smooth  white 
surface,  sprinkled  with  some  seeds  and  insects,  the  hoods 
were  removed,  and  the  creatures'  acts  were  carefully  timed 
and  duly  recorded  in  a  note-book. 

"  Often  at  the  end  of  two  minutes,"  Spalding  says,  "  they 
followed  with  their  eyes  the  movements  of  crawling  insects,  turn- 
ing their  head  with  all  the  precision  of  an  old  fowl.  In  from  two 
to  fifteen  minutes  they  pecked  at  some  speck  or  insect,  showing 
not  merely  an  instinctive  perception  of  distance,  but  an  orioinal 
ability  to  judge,  to  measure  distance,  with  something  like  infallible 

accuracy They  never  missed  by  more  than    a  hair's 

breadth,  and  that  too,  when  the  specks  at  which  tliuy  aimed  were 
no  bigger,  and  less  visible,  than  the  small  dot  of  an  V 

Here,  in  some  detail,  is  an  account  of  the  doings  of 
one  of  these  chicks  immediately  after  it  was  unhooded  : 

"  For  six  minutes  it  sat  chirping  and  looking  about  it;  at  the  end 
of  that  time  it  followed  with  its  head  and  eyes  the  movements  of  a 
fly  twelve  inches  distant;  at  ten  minutes  it  made  a  peck  at  its  own 
toes,  and  the  next  instant  it  made  a  vigorous  dart  at  the  fly,  which 
had  come  within  reach  of  its  neck,  and  seized  and  swallowed  it  at 
the  first  stroke ;  for  seven  minutes  more  it  sat  calling  and  looking 
about  it.  when  a  hive-bee  coming  sufficiently  near,  was  seized  at  a 
dart  and  thrown  some  distance,  much  disabled.  For  twenty  minutes 
it  sat  on  the  spot  where  its  eyes  had  been  unveiled,  without  attempt- 
ing to  walk  a  step.  It  was  then  placed  on  rough  ground,  within 
sight  and  call  of  a  hen  with  a  brood  of  its  own  age.  After  stand- 
ing chirping  for  about  a  minute,  it  started  off  towards  the  hen, 
displaying  as  keen  a  perception  of  the  qualities  of  the  outer  world, 

•  *  "  Macmillan's  Magazine,"  February,  1873. 


Chap.  XIL]  aND    PERCEPTION.  180 

as  it  was  ever  likely  to  possess  in  afterlife.  ...  It  leaped  over 
the  smaller  obstacles  that  lay  in  its  path,  and  ran  round  the  larger, 
reaching  the  mother  in  as  nearly  a  straight  line  as  the  nature  of 
the  ground  would  permit." 

Experiments  were  also  made  with  regard  to  the  sense  of 
Hearing.  Chicks  before  they  had  fully  escaped  from  the 
shell  were  rendered  more  or  less  deaf  by  sealing  their  ears 
with  several  folds  of  gummed  paper.  Three  of  them  were 
found,  when  thus  treated,  to  be  so  deaf,  that  they  remained 
perfectly  indifferent  to  the  voice  of  the  mother,  separated 
from  them  by  only  an  inch  board.  After  having  been  kept 
in  a  bag  in  a  dark  room  till  they  were  between  two  and 
three  days  old,  the  ears  of  these  three  chicks  were  uncovered, 
and,  Spalding  says,  "  on  being  placed  within  call  of  the 
mother,  hidden  in  a  box,  they,  after  turning  round  a  few 
times,  ran  straight  to  the  spot  whence  came  what  must  have 
been  very  nearly,  if  not  actually,  the  first  sound  they  had 
ever  heard."  These  facts  are,  as  he  adds,  "conclusive 
against  the  theory  that,  in  the  history  of  each  life,  sounds 
are  at  first  but  meaningless  sensations  ;  that  the  direction 
of  the  sounding  object,  together  with  all  other  facts  con- 
cerning it,  must  be  learned  entirely  from  experience." 

But  just  as  young  Chicks  follow  the  call  of  their  mother 
before  they  have  had  any  opportunity  of  associating  that 
sound  with  pleasurable  feelin^^s,  so  do  they,  and  other 
young  birds,  appear  to  be  inspired,  independently  of  all 
education  on  their  part,  with  an  immediate  Emotion  of 
dread,  or  sense  of  danger,  at  the  sight,  or  on  first  hearing 
the  cry,  of  birds  of  prey,  whose  predecessors  have  been 
the  natural  enemies  of  their  predecessors.  Thus,  a  young 
Hawk,  able  to  take  only  short  flights,  was  made  to  hover 
over  a  hen  with  her  first  brood,  then  about  a  week  old. 

"  In  the  twinkling  of  an  eye,"  says  Spalding,  "  most  of  the 
chickens  were  hid  among  grass  and   bushes.      The  hen  pursued 


190  SENSATION,    IDEATION, 

it,  aud  scarcely  had  the  hawk  touched  the  ground,  about  tweW« 
yards  from  where  she  had  been  sitting,  when  she  fell  upon  it  with 
such  fury  that  it  was  with  difficulty  that  I  could  rescue  it  from 
immediate  death.  Equally  striking  was  the  effect  of  the  hawk's 
voice  when  heard  for  the  first  time.  A  young  turkey  which  I  had 
adopted  when  chirping  within  the  uncracked  shell,  was,  on  the 
morning  of  the  tenth  day  of  its  life,  eating  a  comfortable  break- 
fast from  my  hand,  when  the  young  hawk,  in  a  cupboard  ^jnst 
beside  us,  gave  a  shrill  chip,  chip,  chip.  Like  an  arrow  the  poor 
turkey  shot  to  the  other  side  of  the  room,  and  stood  there  motion- 
less and  dumb  with  fear,  until  the  hawk  gave  a  second  cry,  when 
it  darted  out  at  the  open  door,  right  to  the  extreme  end  of  the 
passage,  and  there,  silent  and  crouched  in  a  corner,  remained  for 
ten  minutes.  Several  times  during  the  course  of  that  day  it  again 
heard  these  alarming  sounds,  and,  in  every  instance,  with  similar 
manifestations  of  fear." 

Other  most  interesting  observations  are  cited  concerning 
the  Instinctive  Acts  of  chickens,  ducklings,  and  young 
turkeys,  more  especially  in  reference  to  their  mode  of 
seizure  and  disposal  of  food.*  Facts  are  not  wanting, 
moreover,  to  show  that  the  same  kind  of  inheritance  of 
mental  and  bodily  capacities,  and  of  likes  and  dislikes, 
obtains  among  higher  animals.  Instances  of  this  will 
be  given  in  a  subsequent  chapter. f  One,  however,  may 
here  be  cited.  •» 

"  So  old  is  the  feud,"  says  Spalding,J  "  between  the  cat  and  the 
dog,  that  the  kitten  knows  its  enemy  before  it  is  able  to  see  him, 
and  when  its  fear  can  in  no  way  serve  it.  One  day  last  month, 
after  fondling  my  dog,  I  put  my  hand  into  a  basket  containing  four 
blind  kittens,  three  days  old.  The  smell  my  hand  had  carried  with 
it  set  them  puffing  and  spitting  in  a  most  comical  fashion." 

Facts  of  the  kind  above  cited  enabled  Douglas  Spalding 
to  deduce  the  following  all-important  conclusions : — 
(1)  That  young  chickens  can  display  an  intuitive  Perception 

*  "  Macmillan's  Magazine,"  pp.  287  and  288.     t  See  pp.  211,  229. 
X  "  Nature,"  Oct.  7,  l'<7^,  p.  507. 


CiiAP.  XII.]  AND    PERCEPTION.  191 

by  the  Eye  of  the  primary  qualities  of  the  external  world, 
as  well  as  an  appreciation  of  the  distance  and  direction  of 
sounds  on  the  occasion  of  the  first  exercise  of  the  Ear ; 
(2)  That  chickens  instinctively  bring  into  action  Muscles 
that  were  never  so  exercised  before,  and  perform  a  series 
of  delicately  Adjusted  Movements  ending  in  the  accom- 
plishment of  a  definite  act — independent  of  any  antece- 
dent experience,  and,  therefore,  of  any  *  conception  '  of 
such  act ;  (3)  That  **  in  the  more  important  concerns  of 
their  lives  animals  are  guided  by  Knowledge  which  they 
individually  have  not  gathered  from  experience." 

Other  facts  illustrative  of  these  truths  will  be  found 
recorded  in  the  chapter  on  *  Instinct.' 

General  Statement  of  Results.  Our  brief  survey  of 
the  structure  of  Nervous  Systems,  in  passing  from  their 
simplest  forms  to  those  possessed  by  Birds,  has  shown 
that  they  tend  to  become  more  and  more  complex  as 
animals  rise  in  the  scale  of  organization.  We  have  also 
seen  reason  for  believing  that  the  Mental  and  Motor 
phenomena,  of  which  such  organisms  are  capable,  show 
a  similar  tendency  to  increase  in  complexity. 

The  increase  in  structural  complexity  is  brought  about 
by  the  growth  and  development  of  nerve-tissues  m  the  indi- 
vidual under  the  stimulus  of  sensory  *  experience  ' ;  aided 
by  the  continuation,  through  the  principle  of  heredity, 
of  such  new  developments  in  succeeding  individuals.  By 
the  more  or  less  universal  repetition  of  such  processes 
along  difi'erent  lines  of  development,  slow  structural  pro- 
gressions have  been  achieved;  and  with  them  have  arisen 
corresponding  developments  of  function  in  the  direction  of 
Mental  and  Motor  Phenomena.  Just  as,  in  the  individual, 
the  appearance  of  new  structure  and  the  occasional  mani- 
festations of  new  function  have   been  coeval ;  so  the  *  in- 


192  SENSATION,    IDEATION, 

heritance '  of  any  particular  nervous  structures  carries  with 
it  the  possibility  of  manifesting  (on  fit  occasions)  the  func- 
tional activities  with  which  such  structures  have  previously 
been  in  relation  in  ancestral  forms — whether  these  activi- 
ties have  been  concerned  with  more  or  less  complex  Mental 
Phenomena,  or  in  evoking  complex  Muscular  Movements. 
«  We  have  seen  that  the  Nervous  Systems  in  Invertebrates 
generally,  are  composed  of  Ganglia  variously  connected 
together,  some  of  which  are  in  relation,  by  means  of 
*  ingoing '  nerves,  with  impressible  surfaces  or  special 
Sense  Organs ;  while  others  are  in  relation  with  Muscles 
and  Glands  through  the  intervention  of  '  outgoing  '  nerve 
fibres.  Such  surfaces  and  organs  are,  therefore,  the  inlets 
of  all  imj)ressions  by  which  the  Organism  attains  a  Know- 
ledge of,  or,  in  other  words,  is  brought  into  relation  with, 
the  External  World.  The  celebrated  phrase  of  the  school- 
men, 'nihil  est  in  intellectu  quod  nonfiierit  j^riusin  sensu,^ 
w^ould  seem,  therefore, — so  far  as  it  is  applicable  at  all — 
to  be  a  mere  truism  for  all  lower  animals,  whose  Brain  is 
represented  by  a  mere  congeries  of  Ganglia  in  connection 
with  impressible  surfaces  and  more  special  Sense  Organs. 

But  we  have  seen  how  these  Sensory  Ganglia  increase 
in  size  and  tend  to  grow  into  closer  relations  with  one 
another  in  higher  Mollusks  and  in  Insects  ;  how  in  Fishes, 
Beptiles,  and  Birds  they  undergo  a  still  further  develop- 
ment in  each  class — nay,  more,  how  in  these  lower  Verte- 
brates certain  new  co-ordinating  ganglia  known  as  Cere- 
bral Lobes  appear,  in  intimate  structural  relation  with 
the  several  sensory  ganglia,  and  which  notably  increase  in 
their  proportional  size  as  we  pass  from  Fishes  to  Eeptiles, 
and  from  Ptcptilcs  to  Birds. 

But  let  the  reader  also  bear  in  mind  v;hat  has  been  set 
forth  in  the  present  chapter- — How  philosophers  in  all 
times  have  recognized  that  no  Impressions  or  Sensaticns 


CiiAP.  XIL]  AND    PERCEPTION.  193 

can  be  realized  without  an  accompanying  Intellectual 
Activity,  and  that  though  such  activity  is  simple  and  rudi- 
mentary, in  the  case  of  simple  Sensations,  it  becomes 
more  definite  and  complex  with  the  increasing  many- 
sidedness  of  the  multiplying  Perceptions  of  higher 
animals.  He  will  then  dimly  see  how  an  increase  of 
Sensorial  Activity  in  successive  generations  of  animals 
necessarily  involves  a  corresponding  increase  in  Instinc- 
tive and  Intellectual  Activity,  associated,  as  we  shall  find, 
with  a  growing  wealth  of  Emotion  and  more  than  the 
germs  of  Volition.  He  will  then,  too,  be  able  better  to 
realize  the  full  significance  of  the  increasing  development 
and  the  knitting  together  of  the  sensory  ganglia  which  at 
first  compose  the  Brain,  and  the  subsequent  appearance 
of  separate  organs,  the  Cerebral  Lobes,  in  connection 
with  each  and  all  of  them,  in  which  the  various  substrata 
for  Sensory  Impressions  may  come  into  relation  with  one 
another,  and  in  which,  more  especially,  there  may  develop 
the  structural  correlatives  whose  activity  is  associated 
with  such  Perceptions,  Intellectual  Acts,  Emotions,  and 
Volitions,  as  the  several  creatures  are  accustomed  to 
experience  or  manifest. 

If  we  look,  therefore,  to  the  principles  of  '  heredity ' 
generally,  and  to  such  facts  as  have  been  disclosed  by  the 
observations  of  D.  A.  Spalding,  it  becomes  manifest  that 
the  dogma  of  the  schoolmen,  already  quoted,  supported  as 
it  was  by  Gassendi,  Hobbes,  and  later  still  by  Condillac, 
is  no  more  true  for  individual  animals  above  the  lower 
grades  than  it  is  for  man  himself.  Each  organism  does 
not  acquire  all  its  Knowledge  by  '  experience  '  through  the 
avenues  of  Sense — each  inherits  a  complex  mechanism, 
already  attuned  during  the  lives  of  a  long  line  of  progeni- 
tors to  be  affected  in  certain  ways  and  to  act  in  certain 
modes.     When,  therefore,  the  phrase  or  doguui  '  nihil  est 


194       SENSATION,    IDEATION,    AND    PERCEPTION. 

in  intellectii  quod  non  prius  fuerit  in  se7isu '  was  being 
repeated  some  two  centuries  ago  as  an  embodiment  of  the 
reigning  philosophical  creed  concerning  the  '  Origin  of 
Ideas,'  it  was  with  justice  that  Leibnitz  added — *  nisi 
intellectus  ipse,'  if  we  take  this  latter  phrase,  as  we  may, 
in  accordance  with  Spencer's  luminous  viev/,  to  represent 
the  possibilities  of  intellectual  affection  and  action  be- 
queathed to  an  organism  in  the  already  elaborated  nervoua 
system  which  it  inherits.  Within  this  nervous  system 
lie  latent  the  creature's  *  forms  of  Intuition,'  or  *  forms  of 
Thought,'  which  need  only  the  coming  of  appropriate 
stimuli  to  rouse  them  into  harmonious  action.  It  is  the 
fact  of  the  previous  orderly  organization  of  the  structural 
correlatives  of  mental  processes,  which  causes  some  degree 
of  those  modes  of  mental  affection,  known  to  us  as  Feeling, 
Intellectual  Action,  Emotion,  or  Volition,  to  be  engen- 
dered even  in  the  young  untaught  organism  in  response 
to  suitable  stimuli. 

Thus  the  several  mental '  faculties  '  may  be  said  to  have 
been  making  their  appearance,  and  gradually  becoming 
more  distinct,  during  the  whole  period  in  which  a  build- 
ing-up and  organization  of  Nervous  Systems  has  been  in 
progress. 


CHAPTER   XIIL 

CONSCIOUSNESS    IN   LOWER   ANIMALS. 

Some  of  the  commoK  but  elementary  Conscious  States  of 
Men  having  been  principally  ccnsideied  in  the  last  chap- 
ter, we  have  now  to  turn  our  attention  more  particularly 
to  such  states  in  lower  organisms  and  in  members  of  the 
so-called  *  brute  creation.' 

At  some  stage  in  the  complication  of  the  nervous  actions 
of  lower  organisms,  as  well  as  of  brutes  generally,  there  is 
good  ground  for  inferring  that  the  in-going  molecular 
movements,  which  traverse  nerve  fibres  and  thence  diffuse 
themselves  among  related  groups  of  nerve  cells,  give  rise 
(in  a  way  which  is  inexplicable)  to  what  we  know  and  have 
just  been  considering  as  Feeling  or  Sensation.  The  mere 
molecular  movements  and  changes  in  the  nerve  tissues — 
representing  *  impressions  *  in  t^eir  purely  physical  aspects 
< — are  supposed  to  acquire,  engender,  or,  at  all  events, 
become  associated  with  certain  subjective  phases,  answer- 
ing to  what  we  call  *  States  of  Consciousness.*  Though 
nothing  can  be  known  as  to  the  precise  manner  in  which 
these  supposed  Conscious  States  arise,  it  seems  to  many 
to  be  a  *  legitimate  inference  '  that  a  bond  of  kinship  must 
exist  between  them  and  the  molecular  movements  of  the 
fibres  and  cells  with  which,  as  commonly  admitted,  they 
are  in  some  manner  intimately  related. 

But  the  very  existence  in  lower  animals  of  any  conscious 


196  CONSCIOUSNESS    IN 

states  analogous  to  those  which  we  ourselves  experience,  is 
a  matter  only  of  warranted  inference.  A  word  or  two  in 
explanation,  and  by  way  of  comment,  will  make  the  truth 
of  this  statement  more  obvious. 

All  States  of  Consciousness  whatsoever,  whether  they 
occur  under  the  guise  of  Sensations,  Thoughts,  or  Emotions, 
are  phenomena  which  each  of  us  know^s  only  for  himself, 
and  as  existing  in  himself.  I  see  around  me  fellow-beings 
who  behave  in  many  respects  like  myself,  and  from  the 
fact  of  this  similarity  of  behaviour,  as  well  as  from  what 
they  can  tell  me  (by  articulate  speech),  I  am  able,  legiti- 
mately, to  infer  that  these  other  beings  are  possessed  of 
Feelings  very  similar  to  my  own.  This  inference  (with 
or  without  a  full  realization  of  its  grounds)  we  each  of  us 
make,  and  though  it  has  been  long  recognized  by  a  few,* 
it  should  be  more  generally  known  that  such  an  inference 
is  based  partly  (a)  upon  our  observations  of  the  gestures 
or  movements  of  our  fellow-men,  under  circumstances 
with  which  we  are  ourselves  familiar ;  and  partly  (h)  on 
our  appreciation  of  the  results  of  special  classes  of  move- 
ments, by  which  Emotional  Cries,  Articulate  Speech,  or 
Written  Characters  are  produced.  These  latter,  vocal  or 
graphic,  results  of  special  movements,  are  only  interpret- 
able  after  prolonged  efforts,  during  which  we  leavn  to 
recognize  the  several  Auditory  and  Visual  Symbols,  and 
associate  them  with  corresponding  objects,  acts,  states, 
ideas,  and  their  relations. 

Though  the  conclusion  that  our  fellow-beings  are  sentient 
creatures  like  ourselves,  capable  of  Feeling,  Thinking, 
Desiring  and  Willing,  comes  to  most  of  us  as  a  kind  of 
intuition  or  self-evident  truth,  not  requiring  any  proof,  it 
is  well  that  readers  should  know  on  what  grounds  the 

*  See  Dr.  W.  Alison,  art.  "Instinct,"  "Cyclop,  of  Auat.  and 
Physiol./'  vol.  iii.  p.  27,  1839. 


Chap.  XIII.]  LOWER    ANIMALS.  197 

intuition  really  rests,  in  order  that  they  may  the  more 
clearly  recognize  the  only  means  by  which  it  is  possible  for 
us  to  form  an  opinion  as  to  the  existence  and  nature  of 
Conscious  States  in  the  various  classes  and  tribes  of  lower 
animals. 

Of  course  the  information  obtained  by  us  through 
Language  (whether  spoken,  written,  or  printed)  as  to  the 
Feelings  and  Thoughts  of  our  fellow-men,  is  overwhelmingly 
greater  and  more  certain  than  that  derivable  in  other  ways. 
But  it  is  precisely  this  most  definite  source  of  knowledge 
of  which  we  are  deprived  in  the  case  of  the  lower  animals. 
In  some  of  them  we  find  only  a  more  or  less  vague  emo- 
tional or  gesture  language,  of  which  we  have  examples  in 
the  cries,  chirpings,  or  songs  of  Birds,  and  in  the  sounds, 
facial  movements,  and  more  general  actions  of  Dogs,  Apes, 
and  other  of  the  higher  animals.  But  we  have  not  even 
so  much  as  this  to  reveal  the  nature  of  the  subjective 
states  of  the  great  majority  of  animals.* 

What  means  have  we  then  of  forming  an  opinion  as  to 

*  Though  we  are  not  able  to  understand  very  much  of  their 
language,  it  does  not  at  all  follow  that  animals  of  the  same  kind 
may  not  be  able  to  make  their  emotional  language  understood  by 
one  another.  Swainson  says  ("  Habits  and  Instincts  of  Animals," 
p.  62) : — "  'No  attentive  observer  can  have  watched  them  without 
having  perceived  the  mutual  recognition  of  each  other's  wants 
and  feelings,  which  is  implied  both  by  voice,  look,  and  action.  In 
many  cases,  however,  this  communication  is  doubtless  carried  on 
in  a  way  which  we  cannot  eomprehcnd,  and  by  tones  which  we 
are  at  a  loss  to  interpret.  But  those  intonations  in  the  voice, 
which  we  may  not  be  able  to  catch,  are  perfectly  understood  by 
the  animals  themselves.  It  is  well  known  that  the  ewe  and  her 
lamb  can  distinguish  each  other  even  in  the  most  numerous  flock, 
and  that  when  separated  for  a  time  and  again  turned  loc;se  into 
the  field,  the  latter  instantly  recognizes  the  well-known  voice  of 
its  dam,  and  skips  joyfully  up  to  her  the  instant  it  hears  her 
bleat." 


198  CONSCIOUSNESS  IN 

the  Feelings  and  degrees  of  Intelligence  of  the  various 
representatives  of  the  brute  creation  ?  Our  own  experience, 
and  what  we  believe  to  be  that  of  other  human  beings,  has 
to  be  taken  as  our  guide  and  standard  throughout.  We 
must  watch  the  movements  of  animals  under  particular  but 
varying  circumstances,  in  order  to  judge  of  their  different 
emotional  states,  and  of  the  degree  of  reason  or  instinct 
guiding  their  actions.  But  in  the  case  of  multitudes  and 
multitudes  of  the  lower  organisms,  their  actions  give  us  no 
occasion  for  inferring  the  existence  of  anything  so  complex 
as  Emotion,  Eeason,  or  even  Instinct — it  becomes  a 
question  rather  as  to  whether  there  does,  or  does  not, 
exist  in  them  a  mere  vague  '  sentience,'  such  as  might  be 
included  under  the  word  Consciousness,  in  the  ordinary 
acceptation  of  the  term. 

The  fact,  therefore,  that  this  method  of  inferential  inter- 
pretation is  the  only  one  by  Vv^hich  we  can  in  any  way  form 
an  opinion  as  to  the  Mental  States  of  the  Lower  Animals, 
necessarily  leaves  us  either  altogether,  or  very  much  in  the 
dark,  as  regards  certain  important  questions  to  which 
reference  must  now  be  made. 

(1.)  We  are  wholly  unable  to  determine  what  degree  of 
complexity  the  Nervous  System  must  attain,  before  even 
the  dimmest  and  most  obscure  subjective  manifestations 
analogous  to  what  we  know  in  ourselves  as  Consciousness 
may  result  from  the  actions  taking  place  in  the  principal 
nerve  centre  of  an  organism.  We  cannot,  to  take  an 
example,  at  all  definitely  decide  whether  any  of  the  nerve 
actions  of  the  Oyster,  or  of  the  Earth-worm,  are,  or  are 
not,  attended  by  subjective  states  or  phases,  akin  even  to 
our  dimmest  Sensations.  Nor  can  we  say  whether  any  such 
subjective  states  accompany  the  nerve  actions  of  many 
other  organisms  presenting  Nervous  Systems  of  greater 
complexity. 


Chap.  XIIL]  LOWER    ANIMALS.  199 

The  highest  ganglion  of  an  animal,  or  that  in  which 
the  most  varied  impressions  are  brought  into  relation  with 
one  another,  is  the  part  in  connection  with  which  the 
phenomena  of  Consciousness  will  be  likely  first  to  become 
nascent — as  in  higher  animals  it  will  be  the  part  with  the 
action  of  w^hich  the  most  vivid  Conscious  states  are  likely 
to  be  associated.  On  this  subject,  Herbert  Spencer 
says  :* — "  There  cannot  be  co-ordination  of  many  stimuli 
without  some  ganglion  through  which  they  are  all  brought 
into  relation,  this  ganglion  must  be  subject  to  the  influence 
of  each — must  undergo  many  changes.  And  the  quick 
succession  of  changes  in  a  ganglion,  implying  as  it  does 
perpetual  experiences  of  differences  and  likenesses,  consti- 
tutes the  raw  material  of  Consciousness." 

The  above-mentioned  difficulty  in  ascertaining  when 
Consciousness  begins  to  manifest  itself,  of  course  implies 
a  belief  that  Conscious  States  do  not  necessarily,  as 
some  have  suggested,  accompany  all  nerve  actions.  This, 
indeed,  is  a  truth  revealed  to  us  every  day,  since  multi- 
tudes of  nerve  actions  occur  in  ourselves  and  in  our  fellow- 
men  without  any  appreciable  subjective  accompaniment — 
and  it  would  be  absurd  to  say  we  are  '  conscious  '  of  what 
we  do  not  appreciate.  There  is,  as  previously  indicated, 
an  habitual  absence  of  sensation  or  feeling  of  any  kind 
in  conjunction  with  many  reflex  and  other  nerve  actions. 

This  inference  as  to  the  absence  of  a  subjective  side 
with  many  nerve  actions,  is  allowed  by  nearly  all  physi- 
ologists to  be  strengthened  by  the  occurrence  of  *  reflex 
movements,'  following  unfelt  impressions,  in  persons  wdth 
disease  of  the  spinal  cord — i.e.,  when  this  is  of  such  a 
kind  as  to  prevent  the  passage  of  nerve  currents  to  or 
from  the  brain.  A  similar  conclusion  has  also  been  arrived 
at  by  many  from  a  study  of  the  results  of  experiments  with 
*  "  Principles  of  Psjcliology,"  vol.  i.  p.  435. 


200  CONSCIOUSNESS    IN 

Frogs  and  other  lower  animals,  in  which  the  spinal*cord 
has  been  completely  cut  across  so  as  to  prevent  impres- 
sions reaching  the  hi'ain.  The  adverse  reasoning  of 
G.  H.  Lewes  and  others  would  prove  too  much.  It  would 
warrant  the  belief  that  all  nerve  centres  are  seats  of 
Conscious  Sensibility ;  and  the  acceptance  of  this  view 
would  easily  lead  to  its  extension,  and  soon  make  it 
almost  impossible  to  deny  a  similar  attribute  to  the 
leaves  of  the  Sun-dew  and  other  '  sensitive '  j)lants — or, 
indeed,  to  stop  even  here.  Endless  confusion  might  thus 
be  produced,  without  commensurate  gain. 

A  fairly  legitimate  conclusion  has,  therefore,  been 
drawn,  to  the  effect  that  not  only  do  many  nerve  actions 
exist  which  are  unaccompanied  by  Conscious  States  in  the 
ordinary  acceptation  of  the  term,  but  that  such  nerve 
actions  may  evoke  movements  which  are  just  as  suitable 
and  appropriate,  as  responses  to  the  several  antecedent 
impressions,  as  if  the  movements  in  question  had  actually 
been  evoked  under  conscious  guidance.  The  fact  that 
there  is  an  apparent  '  fitness  '  in  the  movement  which  is 
made  in  consequence  of,  and  as  a  response  to,  a  stimulus, 
does  not  by  any  means  alone  entitle  us  to  infer  that  the 
corresponding  impression  had  a  conscious  side,  or  was  a 
real  Sensation.  It  may  have  been  the  case  or  may  not. 
At  all  events,  it  should  be  recollected  that  the  quality  of 
fitness  decidedly  characterizes  the  motor  responses  to 
many  nerve  actions  belonging  to  tlie  *  reflex  '  category,  as 
occurring  in  ourselves,  and  in  which  the  antecedent 
impression  has  certainly  not  been  attended  by  any  phase 
of  Consciousness.  Fitness  of  response  seems,  indeed, 
as  was  pointed  out  in  a  preceding  chapter,  to  be  almost 
a  matter  of  necessity  for  all  nerve  actions  which  have 
been  sufficiently  often  repeated — even  where  they  occur  in 
simple  organisms  possessing  only  the  most  rudimentary 


CnAP.  XIII.]  LOWER    ANIMALS.  201 

nervous  systems,  and  where,  therefore,  conscious  guidance 
may  have  been  absent  even  at  the  time  when  the  struc- 
tural correlatives  of  the  movements  were  originally  or- 
ganized. 

Yet,  in  spite  of  the  acknowledged  source  of  uncertainty 
in  regard  to  this  criterion,  it  must  be  confessed  that  we  are, 
to  a  great  extent  (for  want  of  any  better  guide),  driven  to 
look  to  this  very  quality  of  'fitness,'  in  reference  to  the 
nature  of  actions  and  the  impressions  which  instigate 
them,  as  our  chief  though  very  uncertain  means  of  form- 
ing an  opinion  concerning  the  probable  presence,  amount, 
or  kind  of  Conscious  Intelligence  in  animals  generally. 
We  have  to  look  especially  to  the  range,  complexity,  and 
degree  of  adaptation  of  the  movements  to  varying  cir- 
cumstances and  to  unfamiliar  conditions;  and  we  aio 
accustomed,  in  addition,  to  look  to  the  degree  of  develop- 
ment of  the  Nervous  System  in  the  animals  under 
observation. 

(2.)  The  same  kind  of  difficulty  presents  itself  in  an- 
other form,  with  regard  to  such  animals  as  Insects,  Cepha- 
lopods.  Fishes,  Eeptiles,  and  Birds.  These  organisms  are 
so  high  in  the  scale  of  organization,  as  to  leave  almost  no 
room  for  doubt  that  some  of  their  nerve  actions  are  attended 
by  Conscious  States,  but  it  is  impossible  for  us  definitely  to 
decide,  which  are,  and  which  are  not,  so  endowed. 

Two  principal  difficulties  stare  us  in  the  face.  First 
there  is  the  necessity  for  the  caution  on  which  we  have  last 
dwelt,  in  respect  to  drawing  conclusions  from  the  degree 
of  *  fitness'  noticeable  in  the  nature  of  the  response  ;  and 
second,  there  is  the  further  difficulty  that  our  own  experience 
can  only  be  taken  as  a  very  uncertain  guide.  Impressions 
of  certain  kinds,  which,  in  ourselves,  are  no  longer  attended 
by  Conscious  States,  may,  nevertheless,  be  commonly  accom- 


202  CONSCIOUSNESS    IN 

pauied  by  some  such  states  in  Cephalopocls  and  Insects,  or 
even  in  lower  Vertebrate  forms.  This,  indeed,  seems 
highly  probable,  judging  from  facts  furnished  by  our  own 
experience.  Each  one  of  us,  after  a  little  reflection,  will 
recall  the  fact  that  many  novel  impressions  or  muscular 
movements,  at  first  associated  with  a  distinct  consciousness 
of  their  performance,  may,  when  they  have  been  often  re- 
peated and  rendered  facile  by  habit,  after  a  time  occur  with- 
out arousing  any  kind  of  Consciousness.  What  has  taken 
place,  therefore,  during  our  own  individual  development, 
probably  has  been  occurring  also  to  a  much  wider  extent 
during  the  gradual  development  of  the  Nervous  System, 
through  the  countless  generations  of  animals,  w^hich,  in 
past  ages  of  the  earth,  have  gradually  been  perfecting 
their  relations  with  the  sum  total  of  their  surroundings. 

It  may  thus  well  happen  that  impressions  which  in 
lower  animals  are  commonly  attended  by  Consciousness, 
gradually  become  in  other  higher  animals  (connected  with 
them  by  descent  and  the  bond  of  kinship)  so  habitual 
that  they  no  longer  arouse  Consciousness.  It  seems  not 
unlikely  that  something  of  the  kind  may,  in  the  course 
of  long  ages  and  with  untold  generations  of  animal 
forms,  have  occurred  with  certain  of  the  most  habitual 
and  least  varied  of  Visceral  Impressions,  and  (though 
to  a  less  extent)  with  other  impressions  emanating  from 
contracting  Muscles  of  all  kinds. 

For  in  organisms  of  greater  Sensorial  and  correspond- 
ingly increased  Mental  Activity,  whose  higher  nerve  cen- 
tres, by  reason  of  these  activities,  become  more  engross- 
ingly  occupied  with  vivid  extrinsic  impressions,  those  of 
an  habitual  character  which  emanate  from  muscles  or 
other  internal  parts  would  probably  less  and  less  engage 
the  animal's  Attention  or  Consciousness.  The  customary 
incitative  or  guiding  impressions  will  still  impinge  upon 


C:iAP.  XIII.]  LOWER    ANIMALS.  203 

higher  nerve  centres,  and  they  may  procure  the  continu- 
ance of  definite  muscular  movements  in  response  to  mere 
unconscious  nerve  actions ;  although,  originally,  the 
occurrence  of  similar  responses  could  only  have  been 
ensured  by  the  directive  and  constructive  influence  apper- 
taining to  an  undivided  Attention  or  Consciousness. 

For  such  reasons  as  these  we  are  robbed  of  all  definite 
grounds  for  anything  like  correct  inference,  as  to  the 
degrees  of  '  sentience  '  accompanying  the  different  nerve 
actions  of  the  countless  hosts  of  lower  animals.  We 
have  a  fair  warrant  for  inferring  that,  in  the  higher  Mam- 
mals, Feeling  is  an  appanage  of  the  action  of  the  same 
kinds  of  nerve  centres  as  suffice  to  evoke  it  in  ourselves — ■ 
however  different  the  Feelings  of  such  creatures  may  be 
in  their  wealth  of  emotional  and  intellectual  accompani- 
ments. But  concerning  the  seats,  so  to  speak,  of  the 
subjective  states  of  animals  lower  than  these,  we  must 
necessarily  remain  very  much  in  the  dark.  We  should, 
indeed,  find  it  difficult  to  disprove,  even  though  we  did 
not  believe,  the  doctrine  of  Descartes,  that  they  in  common 
with  others  were  mere  unconscious  automata. 

(3.)  We  are  not  entitled  to  conclude  that  the  Sensations 
experienced  by  lower  animals,  through  the  intervention  of 
their  various  sense-organs,  have  more  than  a  general 
resemblance  to  the  Sensations  which  we  experience, through 
the  medium  of  what  appear  to  be  corresponding  organs. 

In  some  cases,  indeed,  we  cannot  decide  as  to  the  pre- 
cise kind  of  sense  endowment  which  pertains  to  an  organ 
legitimately  regarded  as  in  some  way  sensitive.  The 
impressions  which  the  Nudibranch  Mollusk  receives 
through  its  large  tentacles,  or  that  the  Insect  receives 
through  its  antennae  in  addition  to  those  of  touch,  may  be 
principally    those   of  smell — or  they  may  be  something 


204  CONSCIOUSNESS    IN 

wholly  different.  Kirb}^  and  Spence,  for  instance,  believe 
it  to  be  through  the  medium  of  their  antennae  that  many 
Insects  are  enabled  to  perceive  approaching  alterations  in 
the  weather.  Bees,  they  say,  seem  in  some  way  to  be- 
come aware  of  the  approach  of  a  shower,  and  hastily 
return  to  their  hives  in  time  to  escape  from  it,  when  we 
may  be  able  to  perceive  no  indications  of  any  atmospheric 
change. 

But,  even  apart  from  this  possible  existence  of  unknown 
modes  of  sentiency  in  some  of  the  lower  animals,  enor- 
mous differences  must  exist  in  regard  to  the  Perceptions 
derived  through  those  channels  of  sense  which  are  more 
or  less  analogous  to  our  own. 

The  actual  nature  and  complexity  of  the  Conscious 
and  Cognitive  States  roused  in  animals  by  external  objects 
will,  necessarily,  be  influenced  by  two  principal  causes. 
First,  their  qualitative  nature  (within  the  sphere  of  each 
sense)  will  depend  upon  the  structural  elaboration  of  the 
several  sense-organs  and  of  their  related  nerve-ganglia,  in 
different  animals.  While,  secondly,  their  complexity  will 
also  be  largely  dependent  upon  the  degree  of  development 
of  the  higher  nerve-centres  as  a  whole,  because,  on  the 
occasion  of  any  impression  upon  an  organ  of  sense,  what  is 
actually  perceived  {i.e.  the  completeness  of  the  Perception) 
depends  principally  upon  the  degree  of  rapid  irradiation  of 
the  impression  to  other  parts  of  the  brain.  The  Percep- 
tions of  similar  objects  by  different  kinds  of  animals  will 
vary  extremely,  as  pointed  out  in  a  previous  chapter,  in 
regard  to  the  number  and  complexity  of  their  components. 
And  these  variations,  as  the  reader  will  easily  understand, 
must  in  the  main  depend  upon  the  average  race-experi- 
ences and  sensorial  endowments  generally  of  the  different 
kinds  of  animals,  in  their  associations  with  the  particular 
objects  perceived. 


Chap.  XIII.]  LOWER    ANIMALS.  205 

The  mere  keenness,  or  discriminative  refinement  of  the 
several  sensory  endowments  in  different  animals,  is  subject 
to  great  variation — the  extremes  being  both  far  below  and 
far  above  the  human  standard. 

Thus  the  Sight  impressions  of  certain  Worms  and 
Mollusks,  obtained  even  at  their  best  through  simple  ocelli, 
can  only  be  regarded  as  of  the  most  vague  and  general 
description,  and  probably  more  or  less  wanting  in  any 
such  accompaniment  as  constitutes  the  conscious  side  of 
our  own  visual  impressions.  But  how  different  is  this 
from  the  same  mode  of  sensorial  activity  in  Birds.  In  a 
lai'ge  majority  of  them,  their  powder  of  vision  seems  far  to 
transcend  that  of  man  or  other  animals,  both  in  regard  to 
range  and  keenness  of  discriminat:on  Sight  is  unques- 
tionably the  dominating  sense  of  Birds. 

"  A  hawk,"  observes  BufFoii,  "  during  its  aerial  soaring,  will 
discern  a  lark  upon  a  clod  of  earth,  coloured  almost  exactly  like 
itself,  at  twenty  times  the  distance  at  which  a  man  or  a  dog  can 
perceive  it.  A  kite,  having  soared  to  an  elevation  beyond  our 
ordinary  vision,  can  distinguish  lizards,  field  mice,  and  small  birds, 
and  select  those  upon  which  he  chooses  to  pounce." 

Again,  the  majority  of  invertebrate  animals  seem  to 
have  extremely  little  power  of  Hearing  or  discriminatiug 
different  kinds   of  sounds.*      Thus   Sir   John   Lubbock 

saySjf — 

"Approaching  an  Ant  which  was  standing  quietly,  I  have 
over  and  over  again  made  the  most  shrill  noises  I  could — using  a 
penny  pipe,  a  dog-whistle,  a  violin,  as  well  as  the  most  piercing 
and  startling  sounds  I  could  produce  with  my  own  voice,  but  with- 
out effect.  At  the  same  time  I  would  by  no  means  infer  from  this 
that  they  are  really  deaf,  though  it  certainly  seems  that  their 
range  of  sounds  is  very  different  from  ours.     We  know  that  certain 

*  See  "  Nature,"  1878,  pp.  640  and  568. 
•j-  "  Journal  of  Linn.  Soc."  (Zool.),  vol.  xiii.  p.  24' 
10 


203  coNscIous^'Ess  in 

allied  insects  produce  a  noise  by  rubbing  one  of  their  abdominal 
rings  against  another.  Landois  is  of  opinion  that  ants  also  make 
Bounds  in  the  same  way,  though  these  sounds  are  inaudible  to  us. 
Our  range  is,  however,  after  all  very  limited,  and  the  universe  ia 
probably  full  of  sounds  v^^hich  we  cannot  perceive.  There  are, 
moreover,  in  the  antennae  of  ants  certain  curious  organs  which 
may  be  of  an  auditory  character." 

Hearing  is,  however,  developed  in  some  respects  to  a 
degree  far  beyond  our  own  in  birds  like  the  Owl,  as  well 
as  in  other  night-flyers.  According  to  Swainson  also, 
the  '*  sense  of  hearing  in  many  quadrupeds  is  particularly 
keen,  and  seems  to  be  given  more  especially  to  the  her- 
bivorous tribes :  thus  the  Elk,  although  not  remarkably 
swift,  is  enabled  to  avoid  its  enemies  by  an  unusual  keen- 
ness in  its  perception  of  sounds.  The  same  delicacy  of 
hearing  is  well  known  to  be  possessed  by  the  Stag."  The 
acuteness  of  this  sense  in  the  Horse,  the  Seal,  and  the 
Porpoise,  is  also  said  to  be  very  remarkable. 

The  sense  of  Touch  in  different  animals  presents  a  wide 
range  of  variation  in  regard  to  its  delicacy  and  discrimi- 
native accompaniments.  Though  always,  to  some  extent, 
a  possible  mode  of  sentiency,  it  does  not  rise  in  many  of 
the  lower  organisms  very  much  beyond  the  level  of  that 
possessed  by  simple  protoplasm.  In  higher  animals, 
however,  it  is  far  different,  and  in  them  the  sense  becomes 
localized  in  some  particular  part  or  parts  of  the  body 
which  are  to  be  regarded  as  the  special  tactile  organs. 

The  sense  of  Touch  is  not  distinctly  localized,  and  prob- 
ably not  very  keen  or  discriminative,  in  Fishes  or  Reptiles, 
though  in  Birds  it  becomes  at  once  more  developed  and 
more  localized. 

Swainson  says, — "In  birds  it  is  probably  confined  to  the  feet 
and  bill.  This  is  particuLirly  aj^parent  in  rapacious  birds,  which 
use  their  feet  in  seizing  and  retaining  their  jjrey ;  while  in  those — 


Chap.  XIIL]  LOWER    ANIMALS.  207 

Buch  as  ducks,  snipes,  and  woodcocks — which  push  their  long  bills 
into  the  mud,  the  point  of  the  mandible  is  not  only  comparatively 
soft,  but  is  often  covered  with  a  very  thin  membranous  skin, 
which  evidently  implies  considerable  sensibility." 

In  the  majority  of  Quadrupeds  tins  sense  is  perhaps 
not  very  highly  developed,  though  as  in  birds  it  seems 
to  be  principally  localized  in  the  paws  and  lips.  There 
are,  however,  two  remarkable  exceptions.  The  trunk  of 
the  Elephant  is  evidently  endowed  with  a  very  keen  and 
discriminative  sense  of  touch,  and  is  to  some  extent  put 
to  the  same  kind  of  use  as  the  four  hands  of  Quadrumana, 
or  the  two  of  human  beings.  The  tactile  endowments  of 
all  these  parts,  however,  in  regard  to  mere  sensitiveness, 
are  altogether  thrown  into  the  shade  by  the  second  excep- 
tion above  referred  to — viz.,  that  presented  by  the  inter- 
digital  membranes,  or  so-called  wings  of  Bats,  and  by  the 
skin  over  their  large  ears.  The  sensitiveness  of  these 
parts  is  so  marvellous  that  it  can  take  the  place  of  sight, 
and  enables  Bats  to  avoid  even  the  most  delicate  obstacles 
in  their  tortuous  and  rapid  flight.  As  Spallanzani  first 
observed,  these  animals  will,  even  when  they  have  been 
blinded,  "  guide  themselves  through  the  most  winding  and 
complicated  passages  without  once  hitting  the  walls,  or 
striking  against  any  impediment  which  may  seem  to 
obstruct  their  progress."  When  in  this  condition  they 
can  even  avoid  coming  into  collision,  during  their  rapid 
gyrations,  with  threads  of  silk  which  have  been  purposely 
stretched  across  a  gallery  or  passage. 

The  three  senses  already  referred  to  constitute  the 
special  intellectual  senses  of  man— those  upon  which 
most  of  his  knowledge  of  the  external  world  is  based. 
There  is,  however,  another  sensorial  endowment — the 
sense  of  Smell — which,  though  it  plays  a  veiy  inconsider- 


208  CONSCIOUSNESS    IN 

able  part  in  ministering  to  the  guidance  of  civilized  human 
beings,  is  of  the  very  greatest  importance  as  an  intellectual 
sense  to  many  different  kinds  of  lower  animals,  and  is  fre- 
quently, like  other  sensorial  endowments,  very  keen  in 
some  of  the  less  civilized  human  races.* 

In  such  creatures  as  Worms,  and  in  the  majority  of 
Mollusks,  it  seems  probable  that  the  sense  of  Smell  is 
either  absent  or  else  extremely  vague  and  indefinite. 
There  is  reason  to  believe  that  it  exists  in  Gasteropods, 
in  the  various  kinds  of  Cuttle-fish,  and  in  many  Crus- 
tacea. In  some  Insects  a  keenly  developed  sense  of 
Smell  appears  to  be  the  dominating  sense  endowment. 
Sir  John  Lubbock  has  shown  that  the  most  intelligent  of 
Insects,  namely  the  social  Ants,  seem  incapable  of  appre- 
ciating sounds,  and  that  they  make  comparatively  little 
use  of  their  small  eyes.  Their  leading  sense  is,  unques- 
tionably, that  of  Smell. f  It  seems  to  be  by  aid  of  this 
faculty  that  they  find  their  w^ay  about,  and  follow  their 
multifarious  daily  avocations.  A  recent  writer,  speaking 
of  the  mode  in  which  Ants  follow  an  established  trail, 
says  I  — 

"  I  have  experimented  with  this,  frequently  obliterating  the 
scent  for  a  space  of  but  a  few  inches,  and  watching  the  puzzled 
wanderers,  each  going  an  inch  or  less  beyond  his  predecessors, 
hunting  the  lost  clue  until  the  blank  was  finally  bridged  over. 
After  that,  if  the  new  route,  as  re-opened,  differed  from  the  old, 
it  was  nevertheless  rigidly  followed,  even  if  longer  and  less 
direct." 

Again,  as  evidence  that  Bees  and  Butterflies  select  the 

*  In  regard  to  this  latter  subject,  many  very  interesting  facts 
will  be  found  recorded  in  Houzeau's  work  "  Lcs  Facultes  Mentalea 
des  Animaux,"  1872,  vol.  i.  pp.  90-94. 

t  '-Journal  of  Linn.  Soc,"  vol.  xiii.  (Zuol.),  pp.  239,  2-14;  and 
"Nature,"  April  10,  1873,  p.  444. 

X  "  Nature,"  February  7,  1878,  p.  282. 


Chap.  XIII.]  LOWER    ANIMALS.  209 

flo.^ers,  which  they  visit  by  means  of  Smell  rather  than 
Sight,  a  writer  says,* — ■ 

"  Bees  particularly,  and  also  butterflies,  visit  a  distinct  variety, 
and  for  the  time  confine  their  attention  to  it,  settling  on  and  suck- 
ing the  honey  of  that  variety  only;  e,g  ,  a  bee  settling  on  a  scarlet 
geranium  will  not  go  from  it  to  another  species  or  variety,  but 

gives  its  attention  to  the  particular  variety  only never 

going  from  a  scarlet  geranium  to  another  scarlet  flower,  even  if  in 

contact I  never   remarked   a  bee  go   from   a  lily   to  an 

amaryllis,  or  the  reverse." 

W.  M.  Gabb,  writing  from  St.  Domingo,  with  regard  to 
the  Butterfly,  says,t — 

"  My  Indian  servants  always  carried  with  them  a  fermented 
paste  of  maize  flower,  which  they  mixed  with  water  to  the  consist- 
ency of  gruel,  as  a  beverage.  On  our  arriving  at  the  side  of  a 
stream  in  a  narrow  gorge,  invariably,  within  a  few  minutes  after 
they  opened  a  package  of  this  paste,  although  there  might  not  have 
been  a  butterfly  in  sight  before,  those  most  brilliant  of  their  kind 
would  come  sailing  up,  always  from  leeward,  and  I  have  made 
some  of  my  best  catches  in  this  manner.  I  have  also  caught  them 
by  baiting  with  a  piece  of  over-i'ipe  or  even  rotten  banana.  At 
other  times  they  were  almost  unapproachable." 

Again,  another  remarkable  fact  points  to  a  similar 
keenness  of  the  sense  of  Smell  in  Moths, t — "  Collectors 
of  Lepidoptera  are  well  aware  that  if  a  virgin  female 
moth  of  a  certain  species  is  enclosed  in  a  box,  males  of 
the  same  species  will  make  their  appearance  from  dis- 
tances which  may  be  relatively  pronounced  prodigious." 

There  seems,  therefore,  good  reason  for  believing  that 
the  actions  of  many  Insects  are  largely  determined  by  a 
subtly  and  highly  discriminative  sense  of  Smell,  which  in 

*  "  :N'ature,"  October  18,  1877. 
t  "I^ature,"  February  7, 1878,  p.  282. 

I  "  Quarterly  Review  of  Science,"  Oct.,  1877.  Art.  "  Our  Six- 
footed  Rivals."    See  also  "Nature,"  July  18,  1878,  pp.  302  and  311. 


210  CONSCIOUSNESS    IN 

acuteness  may  perhaps  rival,  if  it  does  not  exceed,  that  of 
any  other  animal  whatsoever.  In  certain  Insects  with 
enormously  developed  eyes,  however,  such  as  Dragonflies, 
Sight  also  seems  to  he  an  all-important  sense  :  so  that 
Smell  and  Sight  may  he  said  specially  to  guide  the  actions 
of  Insects,  though  not  equally  in  the  same  species. 

The  sense  of  Smell  in  Fishes,  moreover,  seems,  accord- 
ing to  Kirhy,*  to  he  the  most  acute  of  all  their  senses. 

Lacepede  says  : — "  It  may  be  called  their  real  eye,  since  by  it 
they  can  discover  their  prey  or  tlieir  enemies  at  an  immense  dis- 
tance; they  are  directed  by  it  in  the  thickest  darkness,  and  the 
most  agitated  waves.  The  organs  of  this  sense  are  between  the 
eyes.  The  extent  of  the  membrane  on  which  the  olfactory  nerves 
expand  in  a  shark  twenty-five  feet  long,  is  calculated  to  be  twelve 
or  thirteen  square  feet." 

In  a  few  Birds,  such  as  Yultures  and  their  allies,  a  mar- 
vellously keen  sense  of  Smell  was  for  a  long  time  sup- 
posed to  exist,  though  the  ohservations  of  Darwin  and 
others  make  it  probable  that  this  supposition  is  erroneous, 
and  that  the  facts  on  which  it  was  based  may  be  better 
explained  by  the  great  keenness  of  their  sense  of  Sight. 
Certainly  in  the  majority  of  Birds,  the  olfactory  sense 
seems  to  be  very  slightly  developed. 

An  extremely  acute  sense  of  Smell  seems,  however, 
to  exist  with  many  wild  and  domestic  Quadrupeds.  A 
well-known  instance,  belonging  to  the  former  category,  is 
that  of  the  Deer. 

Again  Swainson  writesjf— "The  scent  of  the  American  Bison 
is  said  to  be  so  keen  that  it  is  difficult  for  either  men  or  dogs  to 
get  near  him,  excepting  on  his  leeward  side;  while  the  Camel,  by 
the  perfection  of  the  same  sense,  is  enabled,  while  wandering  over 

*  Kirby's  *'  History,  Habits,  and  Instincts  of  Animals,"  vol.  ii. 
p.  278. 
f  *'  Habits  and  Instincts  of  Animals,"  p.  49. 


CiiAP.  X  II.]  LOWER    ANIMALS.  211 

the  sandy  and  parching  deserts  in  which  he  so  often  ranges,  to  dis- 
cover the  vicinity  of  water  at  the  distance  of  a  mile.'** 

The  keen  scent  of  the  Dog  in  detecting  and  tracking 
various  kinds  of  game,  and  also  in  following  his  master's 
footsteps,  even  in  the  midst  of  a  public  thoroughfare,  is 
familiar  to  all.  There  is  reason  to  believe,  moreover,  that 
the  Dog  habitually  puts  its  sense  of  Smell  to  uses  that  we 
can  only  faintly  realize.  A  good  instance  of  this  sort  is 
cited  by  Dr.  Huggins,f  who  possesses  a  son  of  a  celebrated 
English  Mastiff,  named  Turk,  and  in  whom  he  speedily 
discovered  a  strange  antipathy  to  all  butchers,  and  dislike 
of  butchers'  shops.  On  making  enquiry  of  the  original 
owner  of  Turk,  Dr.  Huggins  found  that  a  similar  anti- 
pathy existed  in  the  father,  and  in  the  grandfather  of  his 
dog,  as  well  as  in  other  sons  of  Turk,  by  different  mothers. 
Concerning  one  of  these  latter  dogs,  named  Paris,  this 
gentleman  communicated  some  most  interesting  facts. 

He  says, — "  Paris  has  the  greatest  antipathy,  as  he  would 
hardly  go  into  a  street  where  a  butcher's  shop  is,  and  would  run 
away  alter  passing  it.  When  a  cart  with  a  butcher's  man  came 
into  the  place  where  the  dogs  were  kept,  although  they  could  not 
see  him,  they  all  were  ready  to  break  their  chains.  A  master- 
butcher,  dressed  privately,  called  one  evening  on  Paris's  master  to 
see  the  dog.  He  had  hardly  entered  the  house  before  the  dog 
(though  shut  in)  was  so  much  excited  that  he  had  to  be  put  into 
a  shed,  and  the  butcher  was  forced  to  leave  without  seeing  the  dog. 

*  U.  C.  ^Norman  writes, — "That  frogs  are  enabled  to  know  when 
water  is  near,  and  that  they  are  instinctively  attracted  towards  it, 
I  have  had  abundant  means  of  certifying  in  localities  where  there 
was  a  pond  on  the  other  side  of  a  paling  or  a  wall.  I  have 
found  irogs,  during  the  spawning  season,  in  numbers,  close  against 
the  impeding  fence,  with  their  heads  towards  it;  and  when  I  threw 
them  ov3r,  they  immediately  proceeded  in  the  direction  of  the 
■water." — White's  **  Natural  History  of  Selborne  "  (Bohn's  edition), 
p.  407. 

i  "  Nature,"  February  13,  1878,  p.  281. 


212  CONSCIOUSNESS    IN 

The  same  dog.  at  Hastings,  made  a  spring  at  a  gentlemnn  who 
came  into  the  hotel.     The  owner  cauglit  the  dog  and  apologized, 
and  said  he  never  knew  him  to  do  so  before,  excei:)t  when  a  butcher  - 
came  to  his  house.      The  gentleman  at  once  said  that  was  his 
business." 

Tills  detection  of  butchers  at  a  distance  and  out  of 
sight,  as  well  as  when  disguised,  could  only  have  been 
brought  about  through  the  dog's  highly  developed  sense 
of  Smell,  enabling  it  to  detect  odours  which  might  well 
be  regarded  as  altogether  inappreciable. 

In  reference  to  a  suggestion  made  by  Mr. Wallace,*  to  the 
effect  that  animals  which  have  been  taken  to  a  distance 
shut  up  in  a  basket,  or  along  a  route  which  they  have  not 
seen,  may,  in  some  instances,  find  their  way  home  princi- 
pally through  the  intervention  of  their  highly  developed 
sense  of  Smell  (a  suggestion  which  gave  rise  to  a  long  and 
very  interesting  discussion).  Prof.  G.  Croom  Robertson 
writes  :t — "Our  external  world  (whether  as  actually 
perceived  or  imaginatively  represented)  may  be  called  a 
world  of  sights  and  touches,  blended  with  and  modifying 

each  other  in  the  most  intimate  way All  other 

sensations,  as  of  hearing,  smell,  and  taste,  come  before 
us  only  discontinuously  and  intermittently,  not  being  had 
from  all  things,  nor  always  from  the  same  things.  But, 
in  a  dog's  experience,  touch  cannot  possibly  co-operate 
with  sight,  as  it  regularly  does  in  ours.  The  organ  of 
effective  touch  in  man — touch  that  gets  associated  with 
vision — is,  in  the  last  resort,  the  hand,  combining  mobility 
and  sensitiveness  in  the  highest  degree  ;  and  the  dog  has 
no  hand.  Its  mobile  limbs  are  not  sensitive  at  the  ex- 
tremities, and,  though  it  has  sensitive  lips,  these,  having 
do   such   active  mobility   as   the   human   hand  has,  are 

*  "Nature,"  February  20,  1873,  p.  303. 
f  "Nature,"  February  27,  1873,  p.  323. 


Chap.  XIII.]  LOWER    ANIMALS.  213 

extremely  limited  in  the  scope  of  their  apprehension.  Its 
touch  being  thus  defective,  what  is  there  then  in  the  dog 
to  play  second  to  sight — which  as  leader  needs  support, 
were  it  only  because  there  is  not  always  light  to  see  with  ? 
Smell,  I  cannot  but  thiuk,  seeing  that,  whilst  the  organ  is 
incontestably  acute,  it  has  the  great  advantage  over  the 
tactile  surface  of  the  lips,  of  receiving  impressions  from 
thiugs  already  at  a  distance.  If  we  only  suppose — what 
the  facts  make  very  likely — that  the  dog's  smell  is  acute 
enough  to  have  some  sensation  from  all  bodies  without 
exception,  nothing  more  is  wanting  to  enable  a  psychologist 
to  understand  that  the  dog's  world  may  be,  in  the  main,  a 
world  of  sights  and  smells  continuous  in  space." 

Horses,  also,  would  seem  to  have  a  similarly  acute  sense 
of  Smell,  and  an  interesting  fact  is  cited  by  Mr.  Darwin 
which  apparently  illustrates  this  point.     He  says,"^ — 

'*  Many  years  ago  I  was  on  a  mail-coach,  and  as  soon  as  we 
came  to  a  public-house,  the  coachman  pulled  up  for  a  fraction  of  a 
second.  He  did  so  when  he  came  to  a  second  public-house,  and  I 
then  asked  him  the  reason.  He  pointed  to  the  off-hand  wheeler, 
and  said  that  she  had  been  long  completely  blind,  and  she  would 
stop  at  every  place  in  the  road  at  which  she  had  before  stopped. 
He  had  found  by  experience  that  less  time  was  wasted  by  pulling 
up  his  team  than  by  trying  to  drive  her  past  the  place,  for  she  was 
contented  with  a  momentary  stop.  After  this  I  watched  her,  and 
it  was  evident  she  knew  exactly,  before  the  coachman  began  to 
pull  up  the  other  horses,  every  public-house  on  the  road,  for  she 
had,  at  some  time,  stopped  at  all.  I  think  there  can  be  little  doubt 
that  this  mare  recognized  all  these  houses  by  her  sense  of  smell." 

It  seems  pretty  certain,  however,  that  many  of  the 
actions  of  lower  animals,  in  finding  their  way  to  distant 
places,  cannot  be  explained  by  reference  to  any  of  the 
senses,  either  singly  or  in  combination,  which  we  have  as 
yet  considered.  How,  for  instance,  is  the  Dog,  the  Cat, 
*  "  Nature,"  March  13,  1873,  p.  360. 


214  CONSCIOUSNESS    IN 

or  tne  Horse,  enabled  to  find  its  way  home  in  a  short  space 
of  time,  through  a  previously  unknown  tiact  of  country, 
and  along  a  route  never  previously  traversed  in  any  way  ? 
How,  again,  is  the  migratory  Bird  able  to  steer  its  way 
across  the  sea,  and  for  thousands  of  miles  back  to  the  same 
chimney,  house-top,  or  bush,  where  in  the  previous  spring 
it  had  built  its  nest  and  reared  its  young  ?  "We  are  com- 
pelled to  assume  that  a  '  Sense  of  Direction '  exists  in 
many  animals,  which  enables  them  wholly  to  transcend 
the  range  of  other  senses. 

This  endowment  occurs  in  such  a  rudimentary  state  in 
the  majority  of  human  beings,  as  to  make  the  correspond- 
ing highly  developed  faculty  of  some  animals  appear  almost 
in  the  light  of  a  wholly  new  and  mysterious  sense  endow- 
ment. 

The  degree  to  which  the  rudiments  of  such  an  endow- 
ment exist  amongst  ourselves,  varies  much  in  different 
individuals.  Some  dwellers  in  cities,  otherwise  highly 
intelligent,  are  almost  incapable  of  finding  their  way  through 
intersecting  streets  to  a  not  very  distant  place,  whose  direc- 
tion was  known  at  the  time  of  starting ;  whilst  others, 
setting  out  with  a  correct  notion  of  the  relative  position  of 
the  place  they  wish  to  reach,  are  easily  able  to  find  it, 
even  though  they  may  have  to  pass  through  a  previously 
unknown  maze  of  turnings.  This  power  of  keeping  a 
'known  direction '  in  mind,  during  many  shiftings  of  direc- 
tion, exists,  however,  in  a  much  higher  degree  in  some 
savage  or  semi-savage  races  of  men.  Thus,  according  to 
Darwin,  Von  Wrangel  has  recorded  the  truly  wonderful 
manner  in  which  the  natives  of  Northern  Siberia  are  able 
to  keep  "  a  true  course  towards  a  particular  spot,  whilst 
passing  for  a  long  distance  through  hummocky  ice,  with 
incessant  changes  of  direction,  and  with  no  guide  in  the 
heavens,  or  on  the  frozen  sea."     North  American  Indiana 


Ci2Ai>.  XIII.]  LOWER    ANIMALS.  215 

bIiow  a  similar  facility  in  finding  their  way  through 
immense  mountainous  tracks,  so  thickly  wooded,  that 
vision  can  only  penetrate  for  a  few  yards  ahead ;  or  over 
pathless  wastes  of  j^rairie  land,  where  a  dreary  sameness 
reigns  supreme.  On  this  subject,  G.  C.  Merrill,  writing 
from  Kansas,  says  :* — 

"I  have  learned  from  the  hunters  and  guides  who  spend  their 
lives  on  the  plains  and  mountains  west  of  us,  that  no  matter  how 
i'ar,  or  with  what  turns,  they  may  have  been  led,  in  chasing  the 
bison  or  other  game,  they,  on  their  return  to  camp,  always  take  a 
straight  line.  In  explanation,  they  say  that,  unconsciously  to 
themselves,  they  have  kept  all  the  turns  in  their  mind."f 

The  excellence  of  this  faculty  in  Siberians,  Indians,  and 
others,  whose  daily  mode  of  life  of  itself  furnishes  strong 
motives  for  cultivating  it,  seems  to  show  that  practice  may 

*  "Nature,"  May  22,  1873,  p.  77. 

f  Referring  to  his  travels  in  the  State  of  Western  Virginia,  Mr. 
Ilenry  Furde  ("  Nature,"  April  17, 1873,  p.  463)  writes  as  follows  :— 
"  It  is  said  that  even  the  most  experienced  hunters  of  the  forest- 
covered  mountains  in  that  unsettled  region  are  liable  to  a  kind  of 
seizure — that  they  '  lose  their  heads  '  all  at  once,  and  become  con- 
vinced that  they  are  going  in  quite  the  contrary  direction  to  what 
they  had  intended,  and  that  no  reasoning  nor  pointing  out  of  land- 
marks by  their  companions,  nor  observations  of  the  position  of  the 
sun,  can  overcome  their  feeling;  it  is  accom])anied  by  great  ner- 
vousness and  a  general  sense  of  dismay  and  'upset.'  The  nervous- 
ness comes  after  the  seizure,  and  is  not  the  cause  of  it.  This  is 
spoken  of  by  the  natives  as  '  getting  turned  round.'  The  feeling 
sometimes  ceases  suddenly,  or  it  may  wear  away  gradually." 
Colonel  Lodge,  in  his  "Hunting  Grounds  of  the  Far  West,"  1876, 
speaks  of  the  same  kind  of  feelings  seizing  upon,  and  occasionally 
demoralizing,  old  and  experienced  prairie  travellers.  Indian  chiefs 
all  concurred  in  assuring  G.  Catlin  ("  Life  amongst  the  Indians," 
p.  96)  that  "whenever  a  man  is  lost  on  the  prairies,  he  travels  in 
a  circle,  and  also  that  he  invariably  turns  to  the  left;  of  which 
singular  fact,"  the  author  adds,  "I  have  become  doubly  convinced 
by  subsequent  proofs." 


216  CONSCIOUSNESS    IN 

make  perfect  in  this  as  in  other  respects  ;  while  the 
common  want,  or  the  existence  of  the  mere  germs  of  such 
a  faculty,  among  dwellers  in  cities,  leading,  as  they  do, 
an  artificial  and  wholly  different  kind  of  life,  would  seem  to 
suggest  that  with  them  it  is  a  faculty  which  has  lapsed 
through  mere  disuse. 

But  the  peculiarity  in  regard  to  many  animals  is,  that 
they  seem  able  to  preserve,  in  some  marvellous  manner, 
this  initial  knowledge  of  direction,  under  circumstances 
in  which  such  powers  as  Siberians  or  North  American 
Indians  possess,  would  seem  likely  to  be  of  little  avail.  A 
very  suggestive  story  in  reference  to  this  kind  of  potency 
in  the  Horse,  has  been  narrated  by  Mr.  Darwin.  He 
says  :* — 

"  I  sent  a  riding-horse,  by  railway,  from  Kent,  via  Yarmouth, 
to  Freshwater  Bay,  in  the  Isle  of  Wight.  On  the  first  day  that  I 
rode  eastward,  my  horse,  when  I  turned  to  go  home,  was  very 
nnwilling  to  return  towards  his  stable,  and  he  several  times  turned 
round.  This  led  me  to  make  repeated  trials,  and  every  time  that 
I  slackened  the  reins,  he  turned  sharply  round  and  began  to  trot 
to  the  eastward,  by  a  little  north,  which  was  nearly  in  the  direction 
of  his  house  in  Kent.  I  had  ridden  this  horse  daily  for  several 
years,  and  he  had  never  before  behaved  in  this  manuer.  My  ini- 
fvession  was  that  lie  somehow  hnew  the  direction  lohence  he  hid 
been  hw'ght.  I  should  state  that  the  last  stage  from  Yarmouth 
[Isle  of  Wight]  to  Freshwater  is  almost  due  South,  and  along  this 
road  he  had  been  ridden  by  my  groom;  but  he  never  once  showed 
any  wish  to  return  in  this  direction.  I  had  purchased  this  horse, 
several  years  before,  from  a  gentleman  in  my  own  neighbourhood, 
who  had  possessed  him  for  a  considerable  time." 

This  story  is  valuable  and  instructive,  but  as  a  more 
complete  instance  of  a  power  there  only  indicated,  one  of 
the  many  examples  recorded  by  A.  W.  Howitt  of  Gipps- 
land  may  be  quoted.     He  says  :t — 

*  "  Nature,"  March  13,  1873,  p.  360. 
t  "  Nature,"  August  21,  1873,  p.  323. 


V 


Chap.  XIII.]  LOWER    ANIMALS.  217 

"  Mr.  Macldntosh,  of  Dargo,  informs  me  that  about  two  years 
ago,  when  gathering  wild  cattle  on  the  Avon  Eiver,  he  got  away 
from  his  men  down  that  river  for  many  miles  before  he  ascertained 
that  he  was  astray.  Finding  then  that  his  horse  jjersisted  in  going 
in  a  certain  direction,  he  gave  him  his  head,  and  the  horse  went  in 
a  straight  line  to  the  place  where  the  camp  was  fixed,  a  distance  of 
some  ten  miles,  through  a  scrubby  country,  and  without  a  track.'* 

As  another  typical  instance  of  this  kind  of  power  in  a 
Dog,  exercised,  moreover,  after  a  long  interval,  the  follow- 
ing occurrence  may  be  cited  :* — 

"  A  hound  was  sent  by  Charles  Cobbe,  Esq.,  from  Newbridge, 
county  Dublin,  to  Moynalty,  county  Meath,  and  thence,  long  a'ter- 
"wards,  conveyed  to  Dublin.  The  hound  broke  loose  in  Dublin,  and 
the  same  morning  made  his  way  back  to  his  old  kennel  at  New- 
bridge, thus  completing  the  third  side  of  a  triangle  by  a  road  he 
had  never  travelled  in  his  life." 

Powers  akin  to  this  displayed  by  the  Horse  and  the 
Dog  seem  possessed  in  considerable  perfection  by  many 
other  kinds  of  animals,  among  which,  in  ascending 
order,  may  be  mentioned  Insects,  Crabs,  Migratory  Fishes 
and  Birds,  some  Keptiles  as  well  as  such  Quadrupeds  as 
the  Cat,  the  Sheep,  the  Ass,  and  probably  many  others.! 

A  very  remarkable  and  well-attested  example  of  such 
an  endowment  in  this  latter  animal  has  been  cited  by 
Kirby  and  Spencet — 

"In  March,  1816,  an  ass,  the  property  of  Captain  Dundas, E.IST., 
then  at  Malta,  was  shipped  on  board  the  Ister  frigate.  Captain 
Forest,  bound  from  Gibraltar  for  that  island.  The  vessel  having 
struck  on  some  sands  off  the  Point  de  Gal,  at  some  distance  from 
the  shore,  the  ass  was  thrown  overboard  to  give  it  a  chance  of 
swimming  to  land — a  poor  one,  for  the  sea  was  running  so  high 

*  "  Quarterly  Eeview,"  October,  1872. 

\  For  recorded  instances,  see  "  Nature,"  vol.  vii. 

X  "  Introd.  to  Entomology,"  seventh  ed.  18G0,  p.  5D2. 


218  CONSCIOUSNESS    IN 

that  a  boat  whicli  left  the  ship  was  lost.  A  few  days  afterwards, 
however,  when  the  gates  of  Gibraltar  were  opened  in  the  morning* 
the  ass  presented  himself  for  admittance,  and  proceeded  to  the 
stable  of  Mr.  Weekes,  a  merchant,  which  he  had  formerly  occupied, 
to  the  no  small  surprise  of  this  gentleman,  who  imagined  that 
from  some  accident  the  animal  had  never  been  shipped  on  board 
the  Ister.  On  the  return  of  this  vessel  to  repair,  the  mystery  was 
explained;  and  it  turned  out  that  Valiante  (so  the  ass  was  called) 
Lad  not  only  swum  safely  to  shore,  but,  without  guide,  compass,  or 
travelling  map,  had  found  his  way  from  Point  de  Gal  to  Gibraltar, 
a  distance  of  more  than  two  hundred  miles,  which  he  had  never 
traversed  betbre,  through  a  mountainous  and  intricate  country, 
intersected  by  streams,  and  in  so  short  a  period  that  he  could  not 
have  made  one  false  turn.  His  not  having  been  stopped  on  the 
road  was  attributed  to  the  circumstance  of  his  having  been  for- 
merly used  to  whip  criminals  upon,  which  was  indicated  to  the 
peasants,  who  have  a  superstitious  horror  of  such  asses,  by  the 
holes  in  his  ears,  to  which  the  persons  flogged  were  tied." 

In  consideration  of  the  existence  of  facts  of  this  kind,  it 
is  contended  that  we  cannot  possibly  account  for  them  by 
any  conceivable  extension  of  the  senses  of  Smell  and 
Sight;  and  that  we  must  suppose  animals  generally, 
though  unequally,  to  be  endowed  with  a  peculiar  sense 
whereby  they  are  enabled  to  retain,  in  the  midst  of  all 
their  wanderings,  a  constant  perception  or  '  sense  of  direc- 
tion '  of  places  from  which  they  have  been  removed  and 
with  which  they  have  become  intimately  associated. 

Quite  recently,  too,  an  announcement  lias  been  made  by 
M.  E.  Cyon,*  which  will  doubtless,  sooner  or  later,  throw 
much  light  upon  the  question  of  the  Organ  and  Nerve  Cen- 
tres, having  to  do  with  this  assumed  '  sense  of  Direction  * 
which  seems  to  exist,  though  very  unequally,  in  Man  and 
BO  many  of  the  lower  animals. 

M.  Cyon's  researches  have  led  him  to  announce  the 
existence  of  a  more  or  less  independent  Organ  of  Sense 

*  "  Comp.  Kend.,"  31st  December,  1877. 


Chap.  XIIL]  LOWER    ANIMALS.  219 

(in-eviously  regarded  as  one  of  the  parts  of  tlie  organ  of 
Hearing,  of  great  physiological  importance,  which  he  desig- 
nates the  *  sense  of  Space.'  Some  of  his  conclusions  on 
this  subject  are  as  follows  : — 

"  The  Semi-circular  Canals  are  the  peripheral  organs  of 
the  sense  of  Space,  that  is  to  say,  the  impressions  produced 
by  the  excitation  of  the  nerve  expansions  in  the  ampullcB 
of  these  canals  seem  to  form  our  notions  of  the  three 
dimensions  of  space.  The  impressions  from  each  canal 
correspond  to  one  of  these  dimensions." 

"  The  physiological  excitation  of  the  peripheric  termi- 
nations belonging  to  the  organ  of  the  sense  of  Space  occurs 
probably  in  a  mechanical  manner,  by  means  of  the  otoliths 
wdiich  exist  in  the  ampullae.  These  otoliths  will  be  thrown 
into  vibration  by  every  active  or  passive  movement  of  the 
head,  and,  perhaps,  also  by  the  atmospheric  waves  whose 
movements  the  tympanic  membrane  transmits  to  the  liquid 
which  fills  the  system  of  semi-circular  canals." 

"  The  eighth  pair  of  cerebral  nerves  thus  contains  two 
nerves  of  sense  altogether  distinct — the  Auditory  Nerve 
and  the  Space  Nerve  (Raumnerv)."* 

*  All  that  pertains  to  this  difficult  subject  is  still  in  its  infancy. 
Since  the  above  was  in  type  two  articles  have  been  published  on 
the  question  in  this  country,  which,  in  addition  to  exposition  and 
criticism,  contain  references  to  the  literature  of  the  subject.  The 
one,  by  Dr.  Crum  Brown,  is  in  "Nature"  for  October,  1878; 
and  the  other,  bj  Prof.  Groom  Eobertson,  in  "  Mind,"  October, 
1878,  p.  559. 


CHAPTER  XrV, 

INSTINCT  :    ITS  NATURE  AND  ORIGIN. 

We  may,  without  much  difficulty,  convince  ourselves  that 
certain  muscular  actions  are  habitually  going  on  within 
our  bodies  in  a  more  or  less  continuous  fashion,  indepen- 
dently of  Will,  and  even  without  arousing  our  Conscious- 
ness. To  this  class  belong  the  movements  of  the  Heart. 
Again,  we  may  learn  that  other  internal  muscular  actions, 
equally  independent  of  Will  and  free  from  conscious 
accompaniment,  take  place  in  a  distinctly  intermittent 
fashion.  To  this  class  belong  those  contractions  of  the 
Stomach  and  Intestines  which  occur  during  the  digestion 
and  assimilation  of  food.  Again,  we  may  learn  that  stiJl 
other  internal  contractions — such  as  those  concerned  in 
oviposition  or  in  the  birth  of  young — recur  at  much  longer 
intervals,  though  they  are  similarly  independent  of  Will 
and  uninstigated  by  conscious  impressions. 

Other  and  wider  muscular  actions,  partly  internal  and 
partly  external,  also  take  place  in  a  rhythmical  manner  in 
relation  with  systemic  conditions.  The  motions  of  the  dia- 
phragm and  of  the  thoracic  and  abdominal  walls,  in  con- 
nection with  Respiration ,  belong  to  this  category.  These 
movements,  though  in  the  main  independent  of  Will,  are 
capable  of  being  very  considerably  modified  thereby;  and 
while  they  are  most  frequently  unheeded,  they  have  a  very 
recognizable  accompaniment  of  feeling  when  attention  is 
distinctly  turned  to  them. 


Chap.  XIV.]    INSTINCT:    ITS  NATURE  AND  ORIGIN.  221 

Actions  which  take  place  independently  of  Will  as  an 
instigator  and  with  machine-like  regularity,  are,  as  the 
reader  is  now  aware,  known  to  physiologists  as  *  reflex  '  or 
*  automatic'  actions.  All  the  acts  above  mentioned  belong 
to  this  category,  and  these  particular  examples  are  further 
characterized  by  the  fact  that  the  impressions  which  incite 
them  are  altogether  unfelt.  They  are  results,  that  is,  of 
unconscious  impressions.  Many  other  automatic  actions, 
however,  exist — sneezing  and  coughing  being  examples — 
in  which  this  latter  peculiarity  is  wanting. 

But  why,  it  may  be  asked,  are  the  actions  above  speci- 
fied performed  with  such  undeviating  regularity,  and  at 
the  instigation  of  mere  unconscious  impressions  ? 

During  the  untold  ages,  in  which  organisms  have  existed 
with  food-taking  propensities  and  alimentary  canals,  con- 
tractions of  the  Intestine  have  been  ensuing  at  short 
intervals,  in  response  to  the  stimulus  supplied  by  food. 
Since  contractile  Hearts  were  first  evolved,  they  have  never 
ceased  to  beat  in  the  lineal  descendants  of  inconceivably 
numerous  generations  of  slowly  modifying  animal  types. 
The  contractions  of  Oviducts  or  of  the  Womb,  as  well  as 
the  movements  concerned  in  Eespiration,  also  had  their 
beginnings  in  forms  of  life  whose  advent  is  now  buried  in 
the  immeasurable  past. 

Let  us,  however,  place  side  by  side  with  these  consider- 
ations, the  well-known  fact  that  one  of  the  essential 
peculiarities  of  nervous  action  is,  that  movements  which 
are  at  first  executed  slowly  and  irregularly,  may,  after 
numerous  repetitions,  become  rapid  and  regular — more 
especially  if  on  successive  occasions  the  stimuli  are  similar, 
and  nothing  intervenes  to  alter  the  manner  in  which 
the  recurring  acts  are  performed.  It  need  not,  therefore, 
surprise  us — especially  after  what  w^e  have  learned  as  to 
the  genesis  of  '  reflex '  actions — to  find  that  the  contrac- 


222  INSTINCT : 

tions  of  viscera  take  place  automatically,  and  even  in 
response  to  unfelt  impressions. 

But  now  let  us  glance  at  other  incidents  in  association 
with  these  visceral  impressions  and  actions. 

No  *  needs  '  or  '  appetites  '  exist  in  connection  with  the 
action  of  the  Heart,  for  the  very  simple  reason  that  its 
stimulus  is  always  at  hand,  and,  in  the  form  of  arterial  or 
venous  blood,  actually  flows  into  the  several  cardiac  cham- 
bers, after  each  contraction.  It  is  a  little  different  with 
regard  to  the  Respiratory  Organs.  Aerated  water  or  pure 
air  does  not  always  surround  the  organism;  and,  as  a 
consequence  of  this  occasional  absence  of  the  proper  stimu- 
lus, it  is  found  that  under  such  unnatural  conditions  a 
*  respiratory  need,'  or  want,  is  felt.  Owing,  however,  to 
this  being  a  want  of  accidental,  rather  than  of  regular, 
occurrence,  it  never  attains  the  more  definite  and  more 
regularly-recurrent  character  of  an  *  appetite.' 

How  different  is  it  with  the  Alimentary  Canal.  Its  par- 
ticular stimulus  is  not  ever  present  like  that  of  the  heart, 
or  only  occasionally  absent,  as  with  that  of  the  respiratory 
organs ;  it  mostly  has  to  be  sought.  Hence  it  is  that 
the  habitually  recurring  need  reveals  itself  as  a  defi- 
nitely returning  appetite  for  food.  Much  the  same  kind 
of  origin  is  to  be  ascribed  to  the  sexual  appetite,  except 
that  it  is  one  which,  in  organisms  generally,  recurs  at 
more  or  less  distant  intervals.  Just  as  hunger,  however, 
depends,  almost  wholly,  upon  impressions  coming  from 
the  alimentary  canal,  so  does  the  sexual  appetite  depend, 
in  the  main,  upon  particular  states  of  certain  Generati\e 
Organs. 

Any  one,  who  carefully  studies  the  acts  of  lower  animals, 
will  readily  recognize  how  very  large  a  proportion  of  them 
are,  either  immediately  or  remotely,  instigated  by  one  or 
other  of  these  visceral  needs  or  '  appetites.' 


Chap.  XIV.]  ITS    NATURE    AND    ORIGIN.  223 

The  mode  in  which  states  of  viscera  operate  in  deter- 
mining an  organism's  activities  is  not  difficult  to  under- 
stand. It  has  been  previously  pointed  out  that  the 
Stomach  is  always  in  direct  communication  with  the  Brain, 
and  that  the  Generative  Organs  are  also,  either  directly  or 
indirectly,  in  close  connection  therewith.  Impressions, 
therefore,  may  emanate  from  either  of  these  organs,  which 
habitually  pass  on  to  the  principal  nervous  centres,  and 
there  come  into  some  kind  of  relation  with  one  or  more 
of  the  special  sense-centres,  whose  activity  they  serve  to 
heighten.  That  there  is  an  intimate  correlation  between 
visceral  needs  and  sensorial  activity  cannot  be  denied. 
An  appetite  for  food,  or  a  desire  to  find  a  mate,  commonly 
suffices  to  call  certain  sense-centres  into  a  state  of  keen 
receptivity  to  impressions,  and  thus  affords  conscious 
intelligence  an  opportunity  to  come  into  play  for  the  im- 
mediate guidance  of  the  animal  in  its  search  for  what  it 
needs,  and  in  its  execution  of  all  those  acts  to  which  it  is 
prompted  for  the  gratification  of  this  or  that  appetite. 

From  what  has  been  previously  said,  it  will  be  seen  to 
be  almost  an  inevitable  necessity  that  all  acts  which  are 
immediately  responsive  to  visceral  needs,  as  well  as  all 
which  daily  and  habitually  suceeed  some  recurring  impres- 
sion, should  be  the  most  deeply  automatic  in  nature.  The 
mode  in  which  the  representatives  of  each  kind  of  organism 
seize  and  swallow  their  food,  should,  for  instance,  like  the 
action  of  the  viscera,  be  more  or  less  common  to  the  whole  of 
them,  and  performed  with  machine-like  regularity.  And  so 
with  other  actions  which  have,  during  succeeding  ages,  been 
taking  place  in  response  to  particular  sensorial  impressions 
throughout  the  lives  of  untold  generations  of  animals. 

It  would  follow,  therefore,  for  the  same  reason,  that  if, 
with  any  organisms,  the  acts  more  remotely  prompted  by 


224  INSTINCT  : 

visceral  needs  are  performed  amidst  practically  uniform 
conditions,  that  these  acts  would  also  tend  to  exhibit  some 
degree  of  the  same  uniformity — whether  they  are  connected 
with  search  after  or  storing  of  food,  with  capture  of  prey, 
with  sexual  dalliance,  or  with  the  deposition  or  care  of 
eggs  or  young.  The  nerve  tissues  having  to  do  with 
any  mixed  series  of  habitually  recurring  impressions  and 
actions,  would,  in  the  course  of  ages,  come  to  be  so  organi- 
cally knit  together  as  to  permit  of  the  manifestation  of 
a  machine-like  regularity  of  habit,  approximating  to  that 
which  is  observed  in  the  performance  of  the  simpler  acts 
more  immediately  dependent  upon  visceral  stimuli. 

The  possibility  of  executing  any  simple  Instinctive  Acts, 
and  still  more  those  which  constitute  a  complex  series,  can 
only  have  been  built  up  and  definitely  organized  after  suc- 
cessive generations  of  animals  have  been  habitually  sub- 
jected to  the  impressions  to  which  the  acts  are  related,  and 
after  such  impressions  have,  at  last,  invariably  led  to  the 
particular  motor  results  in  question.  We  owe  the  first 
distinct  enunciation  of  this  light-giving  notion  to  Herbert 
Spencer.  He  says  :* — "  Let  it  be  granted  that  the  more 
frequently  psychical  states  occur  in  a  certain  order,  the 
stronger  becomes  their  tendency  to  cohere  in  that  order, 
until  they  at  last  become  inseparable;  let  it  be  granted  that 
this  tendency  is,  in  however  slight  a  degree,  inherited,  so 
that  if  the  experiences  remain  the  same,  each  successive 
generation  bequeaths  a  somewhat  increased  tendency ;  and 
it  follows  that,  in  cases  like  the  one  described,  there  must 
eventually  result  an  automatic  connection  of  nervous 
actions,  corresponding  to  the  external  relations  perpetually 
experienced.  Similarly,  if  from  some  change  in  the 
environment  of  any  species,  its  members  are  frequently 
brought  in  contact  with  a  relation  having  terms  a  little 
♦  "Principles  of  Psychology,"  vol.  i.  p.  439. 


CriAP.  XIV.]  ITS    NATURE    AND    ORIGIN.  225 

more  involved  :  if  the  organization  of  the  species  is  so  far 
developed  as  to  be  impressible  by  these  terms  in  close 
succession  ;  then,  an  inner  relation  corresponding  to  this 
new  outer  relation  will  gradually  be  formed,  and  will, 
in  the  end,  become  organic.  And  so  on  in  subsequent 
stages  of  progress." 

This  clustering  together  and  mutual  dependence  of  the 
organic  representatives  of  certain  impressions  and  acts, 
might  be  expected  to  take  place  more  especially  in  con- 
nection with  an  animal's  search  after,  capture  and  dis- 
posal of,  food;  with  the  construction  of  their  habitations, 
or  the  seeking  out  of  places  of  shelter  ;  also,  in  reference 
to  the  successive  incidents  of  their  amours,  to  the  bc!>t 
disposal  of  their  eggs  (with  possible  migrations  to  effect 
this  object),  or  to  the  proper  care  of  their  young  till  thiy 
are  capable  of  looking  after  themselves.  This,  however, 
covers  the  ground  of  most  of  the  so-called  Instincts, 
which,  as  H.  Spencer  says,  are  to  be  regarded  as  "  or- 
ganized and  inherited  habits"  of  a  more  or  less  intricate 
character. 

In  all  the  more  complex  Instinctive  Acts,  we  have  in 
fact  to  do  with  a  more  or  less  prolonged  series  of  impres- 
sions and  interpolated  muscular  movements  associated 
very  closely,  and  following  one  another  with  a  regularity 
only  a  little  less  marked  than  that  which  characterizes 
the  sequence  of  impressions  and  movements  in  those 
*  reflex  acts  '  described  in  a  previous  chapter.  Instincts 
are  therefore  very  correctly  regarded  as  serial  aggregations 
of  such  reflex  acts,  and  accordingly  they  have  also  been 
named  by  Herbert  Spencer  '  compound  reflex  actions.' 

Although  each  of  the  component  acts  may  (like  reflex 
acts  in  general)  present  purposive  characters,  and,  though 
they  may  be  all  combined  so  as  to  lead  to  a  definite 
end,  there  is  no  reason  for  believing  that  such  '  ends  '  are, 


226  INSTINCT:  / 

of  necessity,  previously  realized  or  imagined  by  the  crea- 
ture performing  the  acts,  any  more  than  the  headless 
frog  realizes  the  '  end '  of  movements  which  seem  to  us 
to  be  distinctly  purposive.    It  may,  however,  be  otherwise. 

Thus  in  many  Instincts  an  abiding  visceral  state  (be- 
getting, as  it  does,  a  corresponding  appetite  or  desire) 
exercises  its  powerful  influence  upon  the  higher  nerve 
centres  generally,  and  so  supplies  a  stimulus  more  or  less 
definitely  realized  prompting  to  a  series  of  sensorially- 
guided  acts,  which,  owing  to  the  similarities  of  the  environ- 
ments of  individuals  of  each  species,  are  subject  to  com- 
paratively little  variation  in  their  successive  steps. 

Broussais,  following  in  the  wake  of  Cabanis,  was  one 
of  the  first  to  point  out  the  great  importance  of  visceral 
states  and  impressions  in  reference  to  Instinctive  Acts. 
Citing  a  well-known,  but  important,  illustration,  he  says  :* 
*'  If,  when  a  hen  is  impelled  to  incubation,  we  dip  her 
belly  several  times  in  cold  water,  the  excitement  dis- 
appears, and  the  kind  of  clucking  which  accompanies  this 
desire  ceases,  together  with  all  the  other  acts  related  to 
the  same  end."  And,  that  there  are  visceral  causes  or 
states  lying  at  the  root  of  the  sexual  instincts  generally, 
may  be  inferred,  among  other  things,  from  the  fact  that 
in  animals  which  have  undergone  certain  mutilations  such 
instincts  remain  in  abeyance.  These  states  are  only  peri- 
odically aroused  in  many  animals,  and  in  Birds,  more  espe- 
cially, we  find  sexual  changes  forming  part  of  the  seasonal 
rhythm  of  bodily  states.  "  The  pairing  of  animals  usually 
begins  to  take  place  in  the  spring  ;  when  the  winter  is 
passed,  the  earth  is  covered  by  verdure  and  adorned  by 
the  various  flowers  that  now  expand  their  blossoms.  .  .  . 
The  birds  sing  their  love  songs ;  the  nightingale  is  now 
'most  musical  most  melancboly';  the  cuckoo  repeats  his 
*  "Traite  de  Physiologie,"  Pt.  I.,  chap.  viL 


CuAP    XIV.l  ITS    NATURE    AND    OIUGIN.  227 

monotonous  note  ;  and  every  other  animal  seems  to  par- 
take of  the  universal  joy."* 

The  principal  Instincts  of  animals  have  been  grouped  by 
naturalists  under  three  heads  : — 

1.  Those  dependent,  immediately  or  remotely,  upon   incita- 

tions  from  the  Alimentary  Canal  [e.f].,  mode  of  seeking, 
capture,  seizing,  storing,  or  swallowing  of  food ;  and 
some  cases  of  migration). 

2.  Those   dependent   upon    incitations    from   the    Generative 

Organs  {e.g.,  pairing,  niclification,  oviposition,  care  of 
young ;  and  some  cases  of  migration). 

3.  Those  dependent  upon  more  general  impressions,  perhaps 

partly  internal  and  partly  external  in  origin  (hyberna- 
tion and  migration). 

These  are  the  classes  considered  by  Kirby  and  other 
writers.  Those  of  the  first  set  are  often  spoken  of  as 
Instincts  of  "  self-preservation,"  and  the  second  as 
Instincts  "devoted  to  the  perpetuation  of  the  species.'* 
But  language  of  this  kind  is  apt  to  be  misleading. 
Animals  under  the  influence  of  these  instincts  cannot 
rightly  be  supposed  to  act  as  a  result  of  reflection,  but 
rather  to  be  at  each  step  (though  more  or  less  guided  by 
memory  and  present  sensorial  impressions)  urged  on  by  a 
*  blind  impulse.'  Although  the  successive  components  of 
Instinctive  Acts  for  the  most  part  lead  to  very  definite 
ends,  apparent  enough  to  the  onlooker,  no  definite  con- 
ception of  the  ultimate  end  to  be  obtained  can  be  commonly 
supposed  to  actuate  the  animal. 

It  is  this  negative  characteristic,  indeed,  which  goes  far 
to  explain  the  essential  peculiarity  of  Instinctive,  as  opposed 
to  Kational,  Acts.  Three  leading  peculiarities  of  these 
Acts  were  given  long  ago  by  Dr.  W.  Alison,!  which  are  as 

*  Kirby's  "  Habits  and  Instincts  of  Animals,"  vol.  ii.  p.  188. 
t  "  Cyclop,  if  Anat.  and  Physiol.,"  vol.  iii.  p.  4;. 


22 >  lysTixcT : 

follows : — (1)  They  are  always  perf«:»nned  by  individaals 
of  tLe  saioe  sptcies  in  nearly,  if  not  in  exactly,  the  same 
niamier.  >2  Xo  experience  or  education  is  required  in 
order  that  the  different  Yolnntary  efforts  requisite  for  these 
actions  may  follow  one  another  \rith  unerriog  precision. 
(3)  They  are  occasionally  seen  to  be  performed  under  cir- 
eiunstances  which  the  onlooker  (ha\ing  regard  to  the  ends 
usually  accomrlisbed  by  the  acts)  recognizes  as  rendering 
them  nugat'irv. 

In  illustration  of  the  first  and  second  peculiarities,  the 
following  quotation  from  Bichat  may  be  cited.  He  said  : 
•*If  we  examine  different  animals  at  the  moment  of 
birth;  vre  siiill  s^e  :hi:  the  special  instiDct  of  each  directs 
the  execu::  :  "    r  moTements.     Young  quadrupeds 

seek   the    __  ::_  :lieir  mothers,  birds  of  the  order 

Gallinaceae  seize  i_:-  :ely  the  grata  which  is  their 
appropriate  nourisL:  '     the  youno^  of  the  carnivor- 

ous birds  merely  c^  _  :_  _  iiiouths  to  receive  the  food 
which  their  parents  bring  to  their  nests." 

The  third  peculiarity  exemplifies  the  'blindness  of 
Instinct,'  and  may  be  illustrated  bj  the  fact  that  Blow-flies 
often  deposit  their  eggs  on  a  plant  (Chenopodium  fcetida) 
whose  odour  resembles  decaying  meat,  though  it  is  quite 
unsuitable  as  a  nidus  for  such  eggs  ;  or  by  the  fact  that 
the  Bee  gathers  and  stores  up  honey  even  in  a  climate 
where  there  is  no  winter ;  by  the  fact  that  a  Hen  will  con- 
tinue to  sit  on  a  pebble  which  has  been  put  in  the  place 
of  an  egof,  and  that  she  shows  the  same  kind  of  solicitude 
for  ducklings  that  have  been  hatched  under  her  as  she 
would  for  chickens  produced  from  her  own  eggs. 

Some  powers  and  instincts  (a)  are  connate:  that  is, 
the  animals  are  capable  of  manifesting  them  almost 
immediately  after  birth,   and  without  the   occurrence   of 


Chap.  XIV.]  ITS    NATUTxE    AND    ORIGIN.  229 

previous  abortive  attempts  and  failures.  D.  A.  Spalding 
says  :* 

"  The  pig  is  an  animal  that  has  its  wits  about  it  quite  aa  soon 
after  birth  as  the  chicken.  I,  therefore,  selected  it  as  a  subject  of 
observcition.  The  following  are  some  of  my  observations :  That 
vigorous  young  pi^js  get  up  and  search  for  tlie  teat  at  oace,  and 
within  one  minute  after  their  entrance  into  the  world ;  that  if  re- 
moved several  feet  from  their  mother,  when  aged  only  a  few  minutes, 
they  soon  find  their  way  back  to  her,  guided  apparently  by  the 

grunting  she  makes  in  an.swer  to   their  squeaking One 

pig  I  put  in  a  bag  tbe  moment  it  was  born,  and  kept  it  in  the 
dark  till  it  was  seven  hours  old,  when  I  placed  it  outside  the  sty, 
a  distance  of  ten  feet  from  where  the  sow  lay  concealed  inside  the 
house.  The  pig  soon  recognized  the  low  grunting  of  its  mother, 
went  along  outside  the  sty,  struggling  to  get  under  or  over  the 
lower  bar.  At  the  end  of  five  minutes,  it  succeeded  in  forcing  itself 
through,  under  the  bar,  at  one  of  the  few  places  where  that  was 
possible.  Xo  sooner  in,  than  it  went  without  a  pause  into  the 
pig-house  to  its  mother,  and  was  at  once  like  the  others  in  its 
behaviour." 

In  other  cases,  however,  powers  or  instincts  [h)  which 
cannot  be  manifested  at  birth  become  developed  after 
days  or  weeks ;  apparently  because,  in  these  cases,  the 
Nervous  Systems  of  the  young  animals  have  to  go  through 
certain  stages  of  development  beyond  those  which  have 
been  attained  at  the  time  when  the  young  leave  the 
oriducts  or  womb  of  the  mother. 

On  this  subject,  D.  A.  Spalding  remarks :  *'  The 
human  infant  cannot  masticate  ;  it  can  move  its  limbs, 
but  cannot  walk,  or  direct  i.s  hands  so  as  to  grasp  an 
object  held  before  it.  The  kitten  just  born  cannot  catch 
mice.  The  newly-hatched  swallow  or  tomtit  can  neither 
walk,  nor  lly.  nor  feed  itself.  They  are  helpless  as  the 
human  infant.     Is  it  as  the  result  of  painful  learning  that 

*  *•  ^[aemillan's  Magazine,"  February,  1S73. 
11 


230  INSTINCT  : 

the  child  subsequently  seizes  an  apple  and  eats  it  ?  that 
the  cat  lies  in  wait  for  the  mouse  ?  that  the  bird  finds  its 
proper  food,  and  wings  its  way  through  the  air  ?  We 
think  not.  With  the  development  of  the  physical  parts, 
comes,  according  to  our  view,  the  power  to  use  them  in 
the  ways  that  have  preserved  the  race  through  past  ages. 
This  is  in  harmony  with  all  w^e  know.  Not  so  the  contrary 
view." 

In  regard  to  some  of  those  powers  which  only  become 
possible  several  days  after  birth,  it  can  be  clearly  shown 
that  they  are  no  more  'learned 'by  the  individual  than  are 
those  which  are  capable  of  being  manifested  immediately 
after  birth.  Some  organisms  are  born  in  a  state  of  greater 
maturity  than  others,  and  in  those  in  which  immaturity  is 
most  marked  (as  in  the  human  infant),  as  well  as  in  those 
in  which  it  is  less  marked,  the  necessary  time  must  elapse 
for  the  several  parts  of  the  body,  and  especially  of  the 
Nervous  System,  to  develop,  before  certain  truly  instinc- 
tive desires  and  acts  are  capable  of  showing  themselves. 
Thus  only  can  we  explain  the  late  appearance  of  many 
Instinctive  Acts  in  animals  generally,  as,  for  instance,  the 
powers  of  flight  shown  by  young,  but  only  recently-fledged, 
Birds  who  have  made  no  previous  attempts  to  fly.  The 
manifestation  of  this  latter  power,  independently  of  learn- 
ing, has  also  been  experimentally  verified  by  Spalding. 

He  placed  some  young  unfledged  Swallows  "in  a  small  box  not 
much  longer  than  the  nest  from  which  they  were  taken.  The 
little  box,  which  had  a  wire  front,  was  hung  on  the  wall  near  the 
nest,  and  the  young  swallows  were  fed  by  their  parents  through 
the  wires.  In  this  confinement,  where  they  could  not  even  extend 
their  wings,  they  were  kept  until  after  they  were  fully  fledged." 
The  birds  were  then  liberated,  and  their  actions  carefully  watched. 
Of  two  young  swallows  which  had  been  cuufined  in  this  manner  till 
their  wings  had  grown,  Spalding  says,  "  Due,  on  being  set  free,  flew 
a  yard  or  two  too  close  to  the  ground,  rose  again  in  the  directiou 


Chap.  XiV]  ITS    NATURE    AND    ORIGIN.  231 

of  a  beech-tree,  which  it  gracefully  avoided;  it  was  seen  for  a  con- 
siderable time  sweeping  ronnd  the  beeches,  and  performing  mag- 
nificent evolutions  in  the  air  high  above  them.  The  other,  which 
was  observed  to  beat  the  air  with  its  wings  more  than  usual,  was 
soon  lost  to  sight  behind  some  trees."  He  adds,  "Titmice,  tomtits, 
and  wrens  I  have  made  the  subjects  of  a  similar  study,  and  with 
similar  results.'* 


The    Plasticity    of   In'-;tinct, 

The  same  careful  observer  says  :*  "  Though  the  instincts 
of  animals  appear  and  disappear  in  such  seasonable  corre- 
spondence with  their  own  wants  and  the  wants  of  their 
offspring  as  to  be  a  standing  subject  of  wonder,  they  have 
by  no  means  the  fixed  and  unalterable  character  by  which 
some  would  disLinguish  them  from  the  higher  faculties  of 
the  human  race.  They  vary  in  the  individuals  as  does 
their  physical  structure.  Animals  can  learn  what  they 
did  not  know  by  instinct,  and  forget  the  instinctive  know- 
ledge which  they  never  learned,  while  their  instincts  will 
often  accommodate  themselves  to  considerable  changes  in 
the  order  of  external  events.'*  He  then  records  the  fol- 
lowing experiment : — ■ 


"  Everybody  knows  it  to  be  a  common  practice  to  hatch  ducks' 
eggs  under  the  common  hen,  though  in  such  cases  the  hen  has  to 
sit  a  week  longer  than  on  her  own  eggs.  I  tried  an  experiment  to 
ascertain  how  far  the  time  of  sitting  could  be  interfered  with  in  the 
opposite  direction.  Two  hens  became  broody  on  the  same  day,  and. 
I  set  them  on  dummies.  On  the  third  day  I  put  two  chicks  a  day 
old  to  one  of  the  two  hens.  She  pecked  at  them  once  or  twice ; 
seemed  rather  fidgety,  then  took  to  them,  called  them  to  her,  and 
entered  on  all  the  cares  of  a  mother.  The  other  hen  was  similarly 
tried,  but  with  a  very  different  result.  She  pecked  at  the  chickens 
viciously,  and  both  that  day  and  the  next  stubbornly  refused  to 
have  anything  to  do  with  them." 

*  "  Katurc,"  October  7,  1875,  p.  507. 


232  INSTINCT  : 

Another  excellent  example  of  the  plasticity  of  Instinct ; 
that  is,  of  the  way  in  which  an  instinct  will  vary  under  new 
conditions,  has  been  recorded  by  G.  J.  Romanes.  This 
ingenious  observer  writes*  : — 

"Three  years  ago  I  gave  a  pea-fowl's  egg  to  a  Brabma  hen  to 
Latch.  The  hen  was  an  old  one,  and  had  previously  reared  many 
broods  of  ordinary  chicliens  with  unnsnal  success,  even  for  one  of 
her  breed.     In  order  to  hatch  the  pea-chick,  she  had  to  sit  one 

week  longer  than  is  requisite  to  hatch  an  ordinary  chick 

The  object  with  which  I  made  this  experiment,  however,  was  that 
of  ascertaining  whether  the  period  of  maternal  care  subsequent  to 
incubation  admits,  under  peculiar  conditions,  of  being  prolonged; 
for  a  pea-chick  requires  such  care  for  a  very  muoh  longer  time  than 
does  an  ordinary  chick.  As  the  separation  between  a  hen  and  her 
chickens  always  appears  to  be  due  to  the  former  driving  away  the 
latter  when  they  are  old  enough  to  shift  for  themselves,  I  scarcely 
expected  the  hen  in  this  case  to  i)rolong  her  period  of  maternal  care, 
and,  indeed,  only  tried  the  experiment  because  I  thought  that  if 
she  did  so,  the  fact  would  be  the  best  one  imaginable  to  show  in 
ivhat  a  high  degree  heredUary  instinct  may  he  modified  by  peculiar 
individual  experience.  The  result  was  very  surprising.  For  the 
enormous  period  of  eighteen  months  this  old  Brahma  hen  remained 
with  her  ever-growing  chicken,  and  throughout  the  whole  of  that 
time  she  continued  to  pay  it  unremitting  attention.  She  never 
laid  any  eggs  during  this  lengthened  period  of  maternal  supervision, 
and  if  at  any  time  she  became  accidentally  separated  from  her 
charge,  the  distress  of  both  mother  and  chicken  was  very  great. 
Eventually  the  sep^aration  seemed  to  take  place  on  the  side  of  the 

peacock In  conclusion,  I  may  observe  that  the  peacock 

reared  by  this  Brah  ma  hen,  turned  out  a  finer  bird  in  every  way  than 
did  any  of  his  brothers  of  the  same  brood  which  were  reared  by 
their  own  mother;  but  that,  on  repeating  the  experiment  next 
year  with  another  Brahma  hen  and  several  pea-chickens,  the  result 
was  different,  for  the  hen  deserted  her  family  at  the  time  when  il 
is  natural  for  ordinary  hens  to  do  so,  and,  in  consequence,  all  the 
pea-chickens  miserably  perished." 

Another  observation  proving  the   modifiability  of  In* 
*  "  Nature,"  October  25,  1875,  p.  553. 


CiiAF.  XIV.]  ITS    NATUllE    AND    ORIGIN.  233 

stiiicts  in  Birds  has  been  recorded  by  the  same  observer, 
and  is  of  great  interest.     He  srys  *  : — 

"  A  bitch  ferret  strangled  herself  by  tryinof  to  squeeze  through  too 
narrow  an  opening.  She  left  a  very  young  iamily  of  three  orphans. 
These  I  gave,  in  the  middle  of  the  day,  to  a  Brahma  hen,  which  had 
been  sitting  on  dummies  for  about  a  month.  She  took  to  them  almost 
immediately,  and  remained  with  them  for  rather  more  than  a  fort- 
night, at  the  end  of  which  time  I  had  to  cause  a  separation,  in 
consequence  of  the  hen  having  suffocated  one  of  the  ferrets  by 
standing  on  its  neck.  During  the  whole  of  the  time  that  the 
ferrets  were  left  with  the  hen,  the  latter  had  to  sit  upon  the  nest, 
for  the  young  ferrets,  of  course,  were  not  able  to  follow  the  hen 
about  as  chickens  would  have  done.  The  hen,  as  might  be  expected, 
was  very  much  puzzled  at  the  lethargy  of  her  offspring.  Two  or 
three  times  a  day  she  used  to  fly  off  the  nest,  calling  npon  her 
brood  to  follow ;  but  upon  hearing  their  cries  of  distress  from  cold, 
she  always  returned  immediately,  and  sat  with  patience  for  six  or 
seven  hours  more.  I  should  have  said  that  it  only  took  the  hen 
one  day  to  learn  the  meaning  of  these  cries  of  distress ;  for  after 
the  first  day  she  would  always  run  in  an  agitated  manner  to  any 
place  where  I  concealed  the  ferrets,  provided  that  this  place  was 
not  too  far  away  from  the  nest  to  prevent  her  from  hearing  the 
cries  of  distress.  Yet  I  do  not  think  it  would  be  possible  to  conceive 
of  a  greater  contrast  than  that  between  the  shrill  piping  note  of  a 
young  chicken  and  the  hoarse  growling  noise  of  a  young  ferret. 
On  the  other  hand,  I  cannot  say  that  the  young  ferrets  ever  seemed 
to  learn  the  meaning  of  the  hen's  clucking. 

"  During  the  whole  of  the  time  that  the  hen  was  allowed  to  sit 
upon  the  ferrets,  she  used  to  comb  out  their  hair  with  her  bill,  in 
the  same  way  as  hens  in  general  comb  out  the  feathers  of  their 
chickens.  While  engaged  in  this  process,  however,  she  used  fre- 
quently to  stop  and  look  with  one  eye  at  the  wriggling  nestful,  with 
an  enquiring  gaze  expressive  of  astonishment.  At  otlier  times,  also, 
her  family  gave  her  good  reason  to  be  surprised,  for  she  used  often 
to  fly  off  the  nest  suddenly  with  a  loud  scream,  an  action  which 
was  doubtless  due  to  the  unaccustomed  sensation  of  being  nipped 
by  the  young  ferrets  in  their  search  for  the  teats.  It  is  further 
worth  while  to  remark  that  the  hen  showed  so  much  uneasiness  of 

*  Log.  cit.,  p.  554. 


234  INSTINCT: 

mind  when  the  ferrets  were  taken  from  her  to  be  fed,  that  at  one 
time  I  thought  she  was  going  to  desert  them  altogether.  After 
this,  therefore,  the  ferrets  were  always  fed  in  the  nest,  and  with 
tills  arrangement  the  hen  was  perfectly  satisfied,  apparently 
because  she  thought  that  she  then  had  some  share  in  tlie  feeding 
process.     At  any  rate,  she  used  to  cluck  when  she  saw  the  milk 

coming,  and  surveyed  the  feeding  with  evident  satisfaction 

Altogether,  I  consider  this  a  very  remarkable  instance  of  the  plas- 
ticity of  instinct.  The  hen,  it  should  be  said,  was  a  young  one,  and 
had  never  reared  a  brood  of  chickens.  A  few  months  before  she 
reared  the  young  ferrets  she  had  been  attacked  and  nearly  killed  by 
an  old  ferret,  which  had  escaped  from  his  hutch.  The  young  ferrets 
were  taken  from  her  several  days  before  their  eyes  were  open." 

This  variability  of  instincts  under  varying  conditions  is  a 
matter  of  considerable  importance  in  enabling  us  better 
to  understand  the  enormous  variety  of  Animal  Instincts 
and  the  mode  in  which  some  of  the  most  complex  and 
extraordinary  of  them  may  have  originated.  On  this 
subject  Mr.  Darwin  says:*  **  Under  domestication  in- 
stincts have  been  acquired,  and  natural  instincts  have 
been  lost,  partly  by  habit,  and  partly  by  man  selecting 
and  accumulating  during  successive  generations  peculiar 
mental  habits  and  actions,  which  at  first  appeared  from 
■what  we  must  in  our  ignorance  call  an  accident.  In  some 
cases  compulsory  habit  alone  was  sufdcient  to  j^roduce  in- 
herited mental  changes  ;  in  other  cases  compulsory  habit 
has  done  nothing,  and  all  has  been  the  result  of  selection 
pursued  both  methodically  and  unconsciously."  Again, 
among  wild  animals  "  changes  of  instinct  may  sometimes 
be  facilitated  by  the  same  species  having  different  instincts 
at  different  periods  of  life,  or  at  diilerent  seasons  of  the 
year,  or  when  placed  under  different  circumstances,  &c. ; 
in  which  case  either  the  one  or  the  other  instinct  might 
be  preserved  by  natural  selection.  And  such  instances  of 
diversity  of  instinct  in  the  same  species  can  be  shown  to 

*  "  Origin  of  Species,"  6th  edition,  1872,  pp.  206,  207,  211,  233. 


C'lAP.  XIV.]  ITS    NATURE    AND    ORIGIN.  235 

occur  in  nature.  .  .  ,  Under  changed  conditions  of  life  it 
is  at  least  possible  that  slight  modifications  of  instinct 
might  be  profitable  to  a  species ;  and  if  it  can  be  shown 
that  instincts  do  vary  ever  so  little,  then  I  can  see  no  diffi- 
culty in  natural  selection  preserving  and  continually  accu- 
mulating variations  of  instinct  to  any  extent  that  was  profit- 
able. It  is  thus,  as  I  believe,  that  all  the  most  complex 
and  wonderful  instincts  have  originated.  As  modifica- 
tions of  corporeal  structure  arise  from,  and  are  increased 
by,  use  or  habit,  and  are  diminished  or  lost  by  disuse,  so 
I  do  not  doubt  it  has  been  with  instincts.  But  I  believe 
that  the  effects  of  habit  are  in  many  cases  of  subordinate 
importance  to  the  eff'ects  of  natural  selection,  of  what  may 
be  called  spontaneous  variations  of  instincts :  that  is  of 
variations  produced  by  the  same  unknown  causes  which 

produce  slight  deviations  of  bodily  structure For 

peculiar  habits  confined  to  the  workers  or  sterile  females, 
however  long  they  might  be  followed,  could  not  possibly 
affect  the  males  and  fertile  females  which  alone  leave 
descendants." 

As  typical  instances  of  the  more  complex  Instinctive 
Acts  may  be  cited  the  web-weaving  and  nest-building 
habits  of  Spiders  ;  the  gathering  and  storing  of  honey, 
together  with  all  the  social  acts  of  Bees  ;  the  slave-making 
and  other  habits  of  Ants  ;  the  migrations  of  Fishes  at 
spawning-time  ;  the  selection  of  site  and  mode  of  ovi- 
position  among  Amphibia ;  the  nest=building  acts  and 
migrations  of  Birds  ;  the  house-building  and  food-storing 
acts  of  Beavers.  There  can  be  little  doubt,  that  if  our 
means  of  knowledge  were  greater  than  it  is,  we  should 
be  able  to  explain  these  and  all  other  Instincts  by  refer- 
ence to  the  doctrines  of  'inherited  acquisition'  and 
*  natural  selection,'  either  singly  or  in  combination. 


CHAPTER  XV. 

NASCENT   REASON,  EMOTION,  IMAGINATION  AND  VOLITION. 

The  views  set  forth  in  preceding  chapters  in  regard  to 
Reflex  and  Instinctive  Actions  permit  certain  important 
corollaries  to  be  deduced  therefrom.  And  should  these  be 
found  to  harmonize  with  many  known  facts,  such  corre- 
spondence of  facts  with  theoretical  deductions  Avill  prob- 
ably be  held  to  afford  additional  evidence  in  favour  of 
the  views  in  question. 

In  this  chapter  we  shall  refer  to  three  such  corollaries, 
and  see  what  evidence  can  be  adduced  in  supj)ort  of  them. 

(1.)  It  would  seem  likely  that, — All  the  detinite  acts  of 
very  low  organisms  would  partake  either  of  the  nature  of 
Reflex  Actions  or  of  the  Simple  Instinctive  Acts  into 
which  these  latter  merge  by  almost  insensible  gradations. 

This  proposition  might  be  expected  to  hold  good  for  all 
the  actions  of  Medusae,  Worms,  and  Mollusks — with  the 
exception,  perhaps,  among  the  latter,  of  some  of  those 
manifested  by  the  active  and  highly  endowed  Ccphalopods. 

A  rude  unfamiliar  touch  of  any  kind  evokes  in  a  Snail, 
on  its  travels,  only  one  set  of  actions :  its  body  and  horns 
contract,  and  the  former  is  drawn  by  its  retractor  muscle 
within  the  shell.  No  other  actions  are  ever  seen  to  follow 
such  a  stimulus.  In  its  daily  walk,  also,  the  various 
movements  of  the  Snail  are  of  the  simplest  kind,  largely 
instigated,  it  would  seem,  by  the  visceral  and  general  con- 
dition known  to  us  as  *  hunger,'   and  only  more  rarely 


Chap.  XV.J  IMAGINATION    AND    VOLITION.  237 

diversified  by  other  promptings.  Intluenced  by  an  *  im- 
pulse,' or  'desire'  for  food,  impressions  of  Smell  and 
Sight  doubtless  guide  the  animal  to  the  plants  on  which  it 
is  accustomed  to  feed,  and  whose  leaves  it  devours  with 
that  accompaniment  of  Feeling,  definite  or  indefinite, 
which  may  pertain  to  its  rudimentary  nervous  actions. 

(2.)  We  might  expect  to  find  that, — The  lower  the  de- 
velopment of  the  Brain  in  those  organisms  which  perform 
any  of  the  more  Complex  Instinctive  Actions,  the  less  fre- 
quently would  anything  like  Reason  appear  to  intervene  in 
their  accidental  relations  with  unfamiliar  phenomena  out- 
side the  range  of  their  ordinary  instinctive  experiences. 

In  order  to  test  the  correctness  of  this  inference,  it 
seems  desirable  to  study  pretty  closely  some  of  the  recorded 
acts  of  those  Social  Insects  of  which  we  know  most,  and 
whose  instincts  are  so  remarkable — such  as  Bees,  Wasps, 
and  Ants.  We  may  thus  be  able  to  arrive  at  some  con- 
clusion as  to  the  extent  to  which,  what  is  ordinarily 
termed  *  Reason,'  seems  to  influence  tiieir  actions.  For- 
tunately, we  have  available  the  records  of  numerous  ex- 
perimental observations  recently  made  by  Sir  John  Lub- 
bock,* and  conducted  with  all  the  care  that  could  be 
desired,  in  regard  to  the  reputed  high  intelligence  of  these 
very  animals.  They,  or,  at  all  events.  Bees  and  Ants,  have 
long  been  the  special  favourites  of  naturalists,  many  of 
whom  have  not  hesitated  to  put  the  most  liberal  construc- 
tions upon  the  acts  and  demeanour  of  their  insect  friends. 
There  has  been,  unquestionably,  a  tendency  to  look  at 
these  acts  from  a  much  too  exclusively  human  point  of 
view. 

This  being  so,  it  was  all  the  more  necessary  that  some 

*  "  Journ.  of  Linn.  Soc.  (Zool,),"  vols,  xii.,  xiii.,  and  xiv. 


238  NASCENT    REASON,    EMOTION, 

skilled  observer  should,  as  Sir  John  Lubbock  has  done, 
make  new  and  special  observations  on  the  subject. 

A  few  illustrations  will  enable  the  reader  to  form  his 
own  judgment,  as  to  the  extent  of  the  power  possessed  by 
the  Social  Insects  of  adapting  themselves  to  unfamiliar 
conditions. 

The  first  instance  shows  forcibly  the  comparative  ina- 
bility of  Bees  to  accommodate  themselves  to  changes  in 
their  environment,  and,  incidentally,  their  lack  of  any 
real  loyalty  or  '  sympathy '  for  their  queen  when  she  is 
away  from  her  customary  surroundings. 

Wishing  to  exchange  his  queen  Bee  for  one  of  another  brtred, 
she  was  placed,  Sir  John  Lubbock  sa3^s,  "with  some  workers  in  a 
box  containing  some  comb."  Under  these  new  and  unaccustomed 
conditions  the  workers  took  no  notice  of  their  queen,  so  that  three 
days  afterwards  she  was  found  "  weak,  helpless,  and  miserable." 
The  next  day  some  bees  were  coming  to  a  store  of  honey  at  the 
observer's  window,  and  he  placed  the  helpless  queen  close  to  them. 
*'  In  alighting,  several  of  them  even  touched  her ;  yet  not  one  of 
her  subjects  took  the  slightest  notice  of  her.  TJie  same  q7teen, 
when  afterwards  placed  in  a  hive,  immediately  attracted  a  number 
of  hees."' 

Another  experiment  also  tends  to  confirm  the  machine- 
like or  undeviating  regularity  of  the  intelligence  of  Bees, 
by  showing  their  difficulty  in  recognizing  food  when  it  is 
placed  under  conditions  slightly  differcLt  from  those  to 
which  they  are  accustomed. 

A  number  of  these  insects  were  noticed  to  be  very  busy  with  some 
berberries,  and  Sir  John  Lubbock  says :  "  I  put  a  saucer  with  some 
honey  between  two  bunches  of  flowers ;  these  were  repeatedly 
visited,  and  were  so  close  that  there  was  hardly  room  for  the  saucer 
between  them,  yet  from  9.30  to  3.30  not  a  single  bee  took  any 
notice  of  the  honey.  At  3.30  I  put  some  honey  on  one  of  the 
bunches  of  ilowers,  and  it  was  eagerly  sucked  by  the  bees;  two 
kept  continually  returning  till  past  five  in  the  evening." 


Ciivp.  XV.]  IMAGINATION    AND    VOLITION.  239 

iVgaiii,  not  to  be  able  to  supplement  one  mode  of  sen- 
sorial guidance  by  another,  as  in  the  follovvmg  shnple  case, 
recorded  by  the  same  able  observer,  reveals  what  seems  to 
be  a.  strange  lack  of  adaptive  intelligence  on  the  part  of 
the  Bee. 

"  At  10.15  I  put  a  bee  into  a  bell-glass,  18  inches  long,  and  with 
a  mouth  6^-  inches  wide,  turning  the  closed  end  to  the  window;  she 
buzzed  about  till  11.16,  when,  as  there  seemed  no  chance  of  her 
getting  out,  I  put  her  back  into  the  hive.  Two  flies,  on  the  con- 
trary, which  I  put  in  with  her,  got  out  at  once.  At  11.30  I  put 
another  bee  and  a  fly  into  the  same  glass ;  the  latter  flew  out  at 
once.  For  half  an  hour  the  bee  tried  to  get  out  at  the  closed  end  ; 
I  then  turned  the  glass  with  the  open  end  to  the  light,  when  she 
flew  out  at  once.  To  make  sure,  1  repeated  the  experiment  once 
more,  with  the  same  result." 

**  Both  bees  and  wasps,"  Sir  John  Lubbock  thinks, 
"  find  their  way  about  by  a  '  sense  of  Direction '  rather  than 
that  of  Sight,  though  the  wasp  does  not  so  helplessly 
ignore  the  latter  source  of  knowledge  as  the  bee  seems  to 
do."  The  Ant,  on  the  contrary,  appears  to  have  scarcely 
any  *  sense  of  Direction.'  It  seems  to  guide  itself  almost 
wholly  by  its  sense  of  Smell,  and,  when  baffled  on  such  a 
track,  wanders  about  vainly,  making  little  or  no  use  of  its 
sense  of  Sight.     This  has  been  most  clearly  shown.* 

Ants  often  take  little,  or,  mostly,  no  notice  of  friends  in 
distress,  or  of  dead  ants  lying  in  their  path,  yet  if  one 
or  two  are  crushed  to  death,  in  some  portion  of  a  fre- 
quented track,  all  those  arriving  just  afterwards  at  the 
spot  appear  to  become  frightened  and  bewildered.  They 
run  hither  and  thither  in  an  excited  manner,  and  soon 
either  w^ander  away  or  return.  This  is,  perhaps,  due  in  the 
main  to  a  very  strong  odour  emanating  from  the  crushed 
Ants,  rather  than  to  any  violent  emotion  produced  by  the 

*  "  Jouru.  of  Linn.  See,"  vol.  xiii.  pp.  239-244 


240  NASCENT    REASON,   EMOTION, 

Biglit  of  dead  comrades,  whom  they  generally  disregard. 
This  notion  is  borne  out  by  the  fact  that  they  behave  in 
almost  the  same  way  if  the  tip  of  the  finger  is  drawn  across 
their  line  of  route  on  a  wall ;  or  if  a  mark  is  made  with  a 
stick  or  a  stone  across  their  route  when  they  are  travelling 
on  the  ground.  These  Insects  appear,  indeed,  to  become 
excited  and  bewildered  in  the  face  of  any  unusual  impres- 
sions coming  through  their  dominating  sense-organs,  and 
this  to  a  degree  proportionate  to  the  strength  and  novelty 
of  such  impressions.* 

The  common  Ants  of  this  country  will  not,  even  under 
strong  temptation,  drop  or  jump  downwards  from  some 
slight  elevation.  Sir  John  Lubbock  frequently  made 
experiments  of  this  kind.  He  introduced  some  ants 
(Lasuis  nlf/er)  to  a  store  of  larvae,  and  after  they  had 
been  engaged  for  some  time  in  removing  them,  he  elevated 
one  portion  of  the  bridge  over  which  they  were  compelled 
to  pass  in  going  back  to  the  larvae,  so  that  this  ele\'ated 
end  of  the  bridge  was  three-tenths  of  an  inch  above  the 
remaining  portion.  The  result,  frequently  repeated,  was 
that,  after  a  while,  and  much  coursing  backwards  and 
forwards,  they  all  "  went  away,  losing  their  prize,  in  spite 
of  most  earnest  efforts,  because  it  did  not  occur  to  them  to 
drop  10  of  an  inch."  f  The  same  observer  adds  : — "  At  the 
moment  when  the  separation  was  made  there  were  fifteen 
ants  on  the  larvae.  These  could,  of  course,  have  returned 
if  one  had  stood  still  and  allowed  the  others  to  get  on  its 
back.  This,  however,  did  not  occur  to  them."  They 
wandered  about  for  a  long  time  in  the  most  aimless 
manner. 

This  apparent  lack  of  ingenuity  and  reluctance  to  drop 
from  small  heights,  as  shown  by  our  English  ants,  is  very 

*  "  Nature,"  vol.  vii.  p.  443 ;  vol.  viii.  pp.  244s  303. 
f  "  J-;um.  of  Linn.  Soc."  (Zool.),  vol.  xiii.  p.  217. 


CuAP.  XV.]  IMAGINATION    AND    VOLITION.  241 

remarkable,  but  certainly  not  common  to  such  creatures 
generally.  This  is  shown  by  facts  communicated  to  Kirby* 
by  Colonel  Sykes,  from  his  own  observation,  concerning 
certain   "  large  black  ants  "  common  in  India. 

"When  resident  at  Poona,"  he  saya: — "the  dessert,  consisting 
of  fruits,  cakes,  and  various  preserves,  always  remained  upon  a 
small  side  table,  in  a  verandah  of  the  dining-room.  To  guard 
against  inroads,  the  legs  of  the  table  were  immersed  in  four  basins 
filled  with  water;  it  was  removed  an  inch  from  the  wall,  and,  to 
keep  off  dust  from  open  windows,  was  covered  with  a  tablecloth. 
At  first  the  ants  did  not  attempt  to  cross  the  water,  but  as  the 
strait  was  very  narrow,  from  an  inch  to  an  inch  and  a  half,  and 
the  sweets  very  tempting,  they  appear,  at  length,  to  have  braved 
all  risks,  to  have  committed  themselves  to  the  deep,  to  have 
scrambled  across  the  channel,  and  to  have  reached  the  objects 
of  their  desires,  for  hundreds  were  found  every  morning  revellino- 
in  enjoyment:  daily  vengeance  was  executed  upon  them  with- 
out lessening  their  numbers ;  at  last  the  legs  of  the  table  were 
painted,  just  above  the  water,  with  a  circle  of  turpentine.  This  at 
first  seemed  to  prove  an  efiectual  barrier,  and  for  some  days  the 
sweets  were  unmolested,  after  which  they  were  again  attacked  by 
these  resolute  plunderers;  but  how  they  got  at  them  seemed  totally 
nnaccountable,  till  Colonel  Syk-es,  who  often  passed  the  table,  was 
surprised  to  see  an  ant  drop  from  the  wall,  about  a  foot  above  the 
table,  upon  the  cloth  that  covered  it ;  another  and  another  suc- 
ceeded. So  that  though  the  turpentine  and  the  distance  from  the 
wall  appeared  effectual  barriers,  still  the  resources  of  the  animal, 
when  determined  to  carry  its  point,  were  not  exhausted,  and  by 
ascending  the  wall  to  a  certain  height,  with  a  slight  effort  against 
it,  in  falling  it  managed  to  land  in  safety  upon  the  table." 

These  seem  to  have  been  acts  prompted  by  'reason,'  but 
they  were  probably  guided  by  a  far  better  sense  of  Sight 
than  is  possessed  by  our  English  ants,  which,  as  Sir  John 
Ijubbock  has  shown,  rely  very  little  upon  this  sense  for 
guidance.  It  is  only  fair  to  point  out,  therefore,  that  the 
seeming  lack  of  intelligence  betrayed  by  our  English  ants, 

*  "  Habits  and  Instincts,*'  vol.  ii.  p.  251. 


242  NASCENT    REASON,    EMOTION, 

from  their  disinclination  to  take  a  small  leap,  may  be  due 
simply  to  their  defective  sight.  A  sense  of  Smell,  how- 
ever keen,  would  scarcely  afford  sufficient  guidance  to 
tempt  an  animal  to  jump,  and  the  very  small  laterally- 
placed  eyes  of  the  English  ants  would  probably  not  be  very 
serviceable  in  the  accomplishment  of  such  an  act. 

Bees  have  been  commonly  reputed  to  show  signs  of 
Compassion  for  their  fellows  when  injury  or  misfortune 
overtakes  them.  In  regard  to  this,  Sir  John  Lubbock 
says  * : — 

"  It  is,  no  doubt,  true  that  when  they  have  got  any  honey  on 
them,  they  are  always  licked  clean  by  the  others ;  but  I  am  satisfied 
that  this  is  for  the  sake  of  the  honey  rather  than  of  the  bee.  On 
the  27th  of  September,  for  instance,  I  tried  with  two  bees:  one  had 
been  drowned,  the  other  was  smeared  with  honey.  The  latter  was 
soon  licked  clean,  of  the  former  they  took  no  notice  whatever.  I 
have,  moreover,  repeatedly  placed  dead  bees  by  honey  on  which  live 
ones  were  feeding,  but  the  latter  never  took  the  slightest  notice  of 
the  corpses."  Further  experiments  confirmed  this  opinion,  as  in  his 
second  paper  (loc.  cit.,  vol.  xii.  p.  231)  Sir  John  Lubbock  says :  "  far 
indeed  from  having  been  able  to  discover  any  evidence  of  affection 
amongst  them,  they  appear  to  be  thoroughly  callous  and  utterly 
indifierent  to  one  another." 

No  evidence  was  forthcoming  to  show  that  the  behaviour 
of  English  Ants  to  wounded  comrades  was  very  different 
(loc.  cit.,  p.  492),  though  it  is  true  that  those  which  were 
marked  and  then  returned  to  their  nests,  usually  had  the 
paint  cleaned  off  by  their  fellows. -f-  But  Mr.  Belt,  in  his 
*' Naturalist  in  Nicaragua,"  cites  some  very  remarkable 
instances  of  sympathetic  helpfulness,  which  were  displayed 
by  '  foraging  Ants '  towards  unfortunate  comrades.  He 
Bays  : — 

"  One  day  when  watching  a  small  column  of  these  ants  (Eciton 
*  Loc.  cit.,  vol.  xii.  p.  128.        f  Loc.  cit.,  vol.  xiii.  p.  230. 


Cbap.  XV.]  IMAGINATION    AND    VOLITION.  243 

hamata)  I  placed  a  little  stone  on  one  of  tliem  to  secure  it.  The 
next  that  approached,  as  soon  as  it  discovered  its  situation,  ran 
backwards  in  an  agitated  manner,  and  soon  communicated  the  in- 
telligence to  the  others.  They  rushed  to  the  rescue  :  some  bit  at 
the  stone  and  tried  to  move  it;  others  seized  the  prisoner  by  the 
legs,  and  tugged  with  such  force  that  I  thought  the  legs  would  be 
pulled  off— but  they  persevered  till  they  got  the  captive  free.  I 
next  covered  one  up  with  a  piece  of  clay,  leaving  only  the  ends  of 
the  antennae  projecting.  It  was  soon  discovered  by  its  fellows, 
which  set  to  work  immediately,  and  by  biting  off  pieces  of  the  clay, 
soon  liberated  it." 

It  is  possible,  however,  tliat  such  acts  as  are  above 
recorded  may  have  been  very  commonly  performed  by 
*  foraging  Ants  *  on  behalf  of  distressed  comrades,  though 
they  are  not  habitual  with  Ants  of  other  species.  It  is 
not  at  all  necessary  to  believe  that  any  definite  communi- 
cations had,  as  Mr.  Belt  suggests,  been  made  to  the  Ants 
which  came  out  to  help.  They  may  have  simply  followed 
their  excited  companion.  Evidence  in  regard  to  this  latter 
point,  so  far  as  ordinary  Ants  are  concerned,  will  presently 
be  cited. 

Again,  the  Social  Insects  have  been  said  to  show  signs 
of  Joy,  by  mutual  caresses,  when  old  comrades  meet  after 
weeks  or  months  of  separation.  But  careful  test  experi- 
ments gave  Sir  John  Lubbock  no  evidence  of  this  behaviour, 
either  with  Bees,  Wasps,  or  Ants.  It  has  been  often  said 
that  the  members  of  one  hive  always  recognize  one  another, 
and  that  strangers  are  driven  out.  This  seemed  to  be  true 
only  in  part.  He  found  that  Bees  knew  and  almost  habi- 
tually returned  to  their  own  hive.  Occasionally,  however, 
they  entered  a  strange  hive,  and  this  without  fear  or 
molestation.  Ants  seem  to  remember  each  other  much 
better  than  Bees.  Sir  John  Lubbock  found*  that  strange 
Ants  were  not  permitted  to  remain  in  a  nest ;  they  were, 

*  Loc.  cit.,  vol.  xiii.  pp.  221-237. 


244  NASCENT    REASON,    EMOTION, 

in  almost  all  cases,  persistently  attacked  and  ultimately 
killed — one  species,  however  {Lasius  flavns),  presented  an 
exception  to  this  rule.  Previous  comrades,  after  a  separa- 
tion of  six  months  or  more,  are  not  received  with  any 
signs  of  cordiality,  though,  at  the  same  time,  their  pre- 
sence is  not  as  a  rule  objected  to,  and  they  soon  appear 
quite  at  home  again.  This  apparent  memory  of  indi- 
viduals pertaining  to  the  same  nest  for  one  another  may, 
perhaps,  after  all,  be  rather  dependent  upon  some  subtle 
discrimination  by  the  sense  of  Smell.  An  Ant  of  a  strange 
colony,  though  belonging  to  the  same  species,  may  present 
some  sensorial  attribute  leading  to  its  recognition  as  an 
intruder ;  whilst  a  member  of  the  same  colony,  even  after 
long  absence,  presenting  no  unusual  characters,  is  not  so 
much  remembered  as  passed  by  in  a  heedless  manner. 

What,  moreover,  are  we  to  infer  as  to  the  memory  or 
ability  to  be  taught  by  their  own  individual  experience  on 
the  part  of  Wasps,  in  the  face  of  the  following  facts  nar- 
rated by  Sir  John  Lubbock  ?* 

A  Wasp  wliich  had  been  marked  for  identification,  smeared  her 
wings  with  syrup,  so  that  she  could  not  fly,  and  as  the  experimenter 
did  not  know  where  her  nest  was,  he  could  not  submit  her  to  the 
before  mentioned  cleansing  operations  of  her  companions.  He 
thought  she  was  doomed,  but,  as  a  last  resource,  resolved  to  wash 
htr  himself,  fully  expecting  "  to  terrify  her  so  much,  that  she  would 
not  return  Hgain."  He,  therefore,  "caught  her,  put  her  in  a  bottle 
half  full  of  water,  and  shook  her  up  well  till  the  honey  was  washed 
olf."  She  was  then  transferred  to  a  dry  bottle,  and  put  in  the  sun. 
When  she  was  dry,  Sir  John  Lubbock  says,  **llet  her  out,  and 
she  instantly  flew  to  her  nest.  To  my  surprise,  in  thirteen  minutes 
she  returned  as  if  nothing  had  happened,  and  continued  her  visits 

to  the  honey  all  the  afternoon This  experiment  interested 

me  so  much,  that  I  repeated  it  with  another  marked  wasp,  this 
tune,  however,  keeping  the  wasp  in  the  water  till  she  wab  quite 
luotionless  and  msensiljle.     Wlien  taken  out  of  the  water  she  soon. 

*  "  Journ.  of  Linn.  Soc,"  vol.  xii.  ]).  lo8. 


Chap.  XV.]  IMAGINATION    AND    VOLITION.  245 

recovered ;  I  fed  her ;  she  went  quietly  away  to  her  nest  as  usual, 
and  returned  after  the  usual  absence.  The  uextraoraing  this  wasp 
was  the  tirst  to  visit  the  honey." 

After  what  has  been  ah-eady  stated,  the  reader  will  not 
be  surprised  to  learn  that  the  careful  enquiries  of  Sir  John 
Lubbock  give  no  support  whatever  to  the  supposition  that 
the  Social  Insects  have  a  kind  of  language  of  their  own. 
He  found  no  evidence  of  their  possessing  a  power  of  com- 
municating with  one  another  by  means  of  their  antennae, 
or  otherwise,  so  as  to  enable  them  "  to  narrate  facts  or 
describe  localities."  His  enquiries  were  carefully  directed 
and  often  repeated,  with  the  view  of  throwing  decisive 
light  upon  this  question  ;  and,  in  opposition  to  the  state- 
meuts  of  HUber  and  Dujardin,  they  seem,  as  he  says,  "to 
show  that  wasps  and  bees  do  not  convey  to  one  another 
information  as  to  food  which  they  may  have  discovered.'* 
He  adds : — "  No  doubt  when  one  wasp  has  discovered  and 
is  visiting  a  supply  of  syrup,  others  are  apt  to  come  too, 
but  I  believe  that  they  merely  follow  one  another.  If  they 
communicated  the  fact  considerable  numbers  would  at  once 
make  their  appearance  ;  but  I  have  never  found  this  to  be 
the  case."  The  experiments  and  observations  made  by 
this  skilful  investigator  with  Ants,  with  the  view  of  throw- 
ing light  upon  this  same  question,  have  been  even  more 
exhaustive  and  carefully  planned,  and  have  led  him  to  the 
following  conclusion*  : — "When  an  Ant  has  discovered  a 
store  of  food  and  others  gradually  flock  to  it,  they  are 
guided,  in  some  cases  by  sight,  while  in  others  they 
track  one  another  by  scent." 

Bees  and  Wasps  again  have  been  imagined  by  some  to 

be  in  the  habit  of  making  known  their  Emotions  to  one 

another  by  means  of  sounds,  which  would  of  course  imply 

that   they  possess   a    sense  of  Hearing.     As   previously 

*  Log.  cit.,  vol.  xii.  p.  485. 


246  NASCENT    REASON,    EMOTION, 

stated  (p.  ■205),  however,  the  same  ohserver  found  that 
neither  Bees,  Wasps,  nor  Ants,  seemed  to  take  the  least 
notice  of  the  most  varied  sounds  produced  in  their  vicinity. 
These  investigations  of  Sir  John  Lubbock  are  the  best 
that  have  ever  been  made  to  really  test,  by  means  of 
carefully  devised  experiments,  the  adaptive  intelligence  of 
the  Social  Insects,  whose  Instinctive  Acts  are  so  compli- 
cated and  marvellous,  and  as  far  as  they  have  yet  gone 
they  suffice  to  show  us  the  very  scanty  grounds  that  exist 
for  crediting  them  with  anything  like  Eeason.  His  ex- 
periments have  revealed,  in  the  great  majority  of  cases, 
a  very  surprising  lack  of  Eeason,  when  even  the  slightest 
departure  from  their  customary  actions  was  alone  need- 
ful, in  order  that  these  Insects — the  most  intelligent  of 
their  class — might  adapt  themselves  to  certain  purposely- 
altered  conditions  in  their  environment. 

(3.)  The  next  corollary  is  the  converse  of  that  which 
has  just  been  illustrated.  It  is  this, — The  higher  the 
development  of  the  Brain  in  those  organisms  which  perform 
any  of  the  more  complex  Instinctive  Actions,  the  more 
frequently  will  acts  of  '  Reason '  appear  to  intervene  in 
their  accidental  relations  with  unfamiliar  phenomena  out- 
side the  range  of  their  ordinary  instinctive  experiences. 

Next  to  those  of  Insects,  the  instincts  of  Birds  are, 
perhaps,  the  most  remarkable,  and  as  the  Brain  and 
Nervous  System  generally  is  so  much  more  highly  deve- 
loped in  Birds  than  it  is  in  Insects,  we  ought,  in  accordance 
with  the  corollary  above  mentioned,  to  find  in  the  former 
a  much  greater  liberty  and  choice  of  action,  together  with 
a  more  decided  and  more  frequent  exercise  of  the  lower 
modes  of  Reason,  Emotion,  Imagination,  and  Volition 
than  is  to  be  met  with  among  the  latter.* 

*It  is  not  meant  for  the  reader  to  infer  that  the  distinct  manifesta* 


Chap.  XV.]  IMAGINATION    AND    VOLITION.  247 

It  will  not,  we  tliiiik,  be  difficult  to  find  evidence  of  the 
existence  among  Birds  of  an  altogether  richer  and  more 
varied  series  of  life  phenomena.  Some  few  illustrations 
will  now  be  cited. 

An  interesting  story  from  the  pen  of  the  Scottish  natu- 
ralist, Thomas  Edwards,  so  much  of  whose  life  has  been 
devoted  to  the  study  of  the  habits  of  the  lower  animals, 
may  first  be  quoted.  It  refers  to  a  little  bird  called  the 
'  Turnstone,'  which  feeds  on  the  small  Sandhoppers  of 
the  sea- shore.  The  acts  cited  seem  to  testify  to  the  exist- 
ence of  a  distinct  imagination  of  an  end  desired,  and  also 


tior,  of  these  mental  states  is  not  met  with  till  we  come  to  animals 
of  this  degree  of  organization.  The  signs  of  Emotion,  for  instance, 
are  most  typical  in  certain  Reptiles.  R  M.  Middleton  says  ("Na- 
ture," October  31st,  1878,  p.  696) : — *'  During  the  past  summer  I 
have  kept  five  Chameleons  in  captivity,  and  have  repeatedly  observed 
their  terror  and  rage  when  confronted  with  snakes.  When  a  large 
Algerian  chameleon,  now  in  my  possession,  perceives  a  common 
snake  wriggling  in  its  vicinity,  he  at  once  inflates  his  body  and 
pouch,  sways  himself  backwards  and  forwards  with  considerable 
energy,  or  walks  rapidly  away  with  his  body  leaning  over  in  the 
direction  farthest  from  the  snake,  opening  his  huge  cavernous 
mouth,  and  hissing,  and  even  snapping  at  what  he  evidently 
regards  as  his  natural  enemy.  At  the  same  time  his  body  assumes 
an  almost  instantaneous  change  of  colour,  and  is  quickly  covered 
with  a  large  number  of  small  brown  spots.  It  is  curious  that  even 
similar  symptoms  of  fear  and  auger  are  displayed  when  a  lizard 
or  even  a  tree-frog  is  exhibited  to  him.  The  climax  of  grotesque 
nervousness  was,  however,  reached  one  day  when  the  sight  of  a 
child's  doll  produced  the  like  effect;  in  this  case  it  is  probable  that 
the  glass  eyes  of  the  doll,  giving  to  it  the  api^earance  of  life,  were 
what  caused  this  terror  in  the  reptile."  The  writer  has  also  lately 
noticed  these  signs  of  anger  or  terror  in  the  chameleon.  The 
swaying  of  the  body  backwards  and  forwards,  together  with  the 
wide  opening  of  its  enormous  mouth,  were  constant  features,  and 
when  the  animal  was  taken  up  at  this  time,  a  peculiar  thrill-like 
vibration  of  the  body  could  be  distinctly  felt. 


243  NASCENT    REASON,    EMOTION, 

of  a  reasoned  and  volitional  adaptation  of  means  to  bring 
about  SQcli  an  end.     T.  Edwards  says  : — 

"Passing  along  the  sea-shore  on  the  west  of  Bantf,  I  observed 
on  the  sands,  at  a  considerable  distance  before  me,  two  bh-ds  beside 
a  large-looking  object.  Stooping  down  with  my  gun  upon  my 
back,  pre]-)ared  for  action,  1  managed  to  crawl  through  the  bents 
and  across  the  shingle  for  a  considerable  way,  when  I  at  length 
came  in  sight  of  the  two  little  workers,  who  were  busily  endeavour- 
ing to  turn  over  a  dead  fish  which  was  fully  six  times  their  size,  I 
immediately  recognized  them  as  turnstones.  Not  wishing  to  dis- 
turb them,  anxious  at  the  same  time  to  witness  their  operations,  and 
observing  that  a  few  paces  nearer  them  there  was  a  deep  hollow 
among  the  shingle,  I  contrived  to  creep  into  it  unobserved.  I  was 
now  distant  from  them  but  about  ten  yards,  and  had  a  distinct  and 
unobserved  view  of  all  their  movements.  .  .  Having  got  fairly  settled 
down  in  my  pebbly  observatory,  I  turned  my  undivided  attention 
to  the  birds  before  me.  They  were  boldly  pushing  at  the  fish  with 
their  bills  and  then  with  their  breasts;  their  endeavours,  however, 
were  in  vain — the  object  remained  immovable.  On  this  they  both 
went  round  to  the  opposite  side,  and  began  to  scrape  away  the  sand 
from  close  beneath  the  fish.  After  removing  a  considerable 
quantity,  they  again  came  back  to  the  spot  which  they  had  left, 
and  went  once  more  to  work  with  their  bills  and  breasts,  but  with 
as  little  apparent  success  as  formerly.  Nothing  daunted,  however, 
they  ran  round  a  second  time  to  the  other  side,  and  recommenced 
their  trenching  operations,  with  a  seeming  determination  not  to 
be  bafiied  in  their  object,  which  evidently  was  to  undermine  the 
dead  animal  before  them,  in  order  that  it  might  be  the  more  easily 
overturned.  While  they  were  thus  employed,  and  after  they  had 
laboured  in  this  manner,  at  both  sides  alternately,  for  nearly  half- 
an  hour,  they  were  joined  by  another  ot  their  own  species,  which 
came  flying  with  rapidity  from  the  neighbouring  rocks.     Its  timely 

arrival  was  hailed  with  evident  signs  of  joy Their  mutual 

congratulations  being  over,  they,  all  three  fell  tc  work,  and  after 
labouriug  vigorously  for  a  few  minutes  in  removing  the  sanl,  they 
came  round  to  the  other  side,  and,  putting  their  breasts  simul- 
taneously to  the  fish,  they  succeeded  in  raising  it  some  inches  from 
the  sand,  but  were  unable  to  turn  it  over.  It  went  down  again  to 
its  sandy  bed,  to  the  manifest  disai)[)oiutment  of  the  three.  Rest- 
ing, however,  for  a  space,  and  without  moving  from  their  respective 


Chap.  XV.]  IMAfUNATIOX    AND    VOLITION.  219 

posiiifms,  which  were  a  little  apart  the  one  from  the  other,  they 
resolved,  it  appearsj,  to  give  the  matter  another  trial.  Lowering 
themselves  npon  their  breasts  close  to  the  sand,  they  managed  to 
push  their  bills  underneath  the  fish,  which  they  made  to  rise  to 
about  the  same  height  as  before;  afterwards,  withdrawing  their 
bills,  but  without  losing  the  advantage  they  had  gained,  they 
applied  their  breasts  to  the  object.  This  they  did  with  such  force, 
and  to  such  purpose,  that  at  length  it  went  over  and  rolled  several 
yards  down  a  slight  declivity.  It  was  followed  to  some  distance 
by  the  birds  themselves  before  they  could  recover  their  bearing. 
They  returned  eagerly  to  the  spot  whence  they  had  dislodged  the 
obstacle  which  had  so  long  opposed  them,  and  they  gave  unmis- 
takable proof,  by  their  rapid  and  continued  movements,  that  they 
were  enj(iying  an  ample  repast  as  the  reward  of  theii  industrious 
and  praiseworthy  labour." 

Again,  a  writer  in  *' Nature"*  describes  an  incident 
witnessed  by  himself  outside  an  Inn  near  Richmond, 
where  some  '  Pouter  '  pigeons  were  feeding.  The  actions 
of  one  of  them  were  of  a  very  unusual  character,  and 
had  in  all  probability  been  learned  by  the  individual 
bird  itself.  It  would  seem,  moreover,  that  they  must 
have  been  undertaken  with  a  pretty  distinct  notion  of  the 
end  to  be  obtained.     The  writer  says  : — 

"A  number  of  them  were  feeding  on  a  few  oats  that  had  been 
accidentally  let  fall  while  fixing  the  nose-bag  on  a  horse  standing 
at  bait.  Having  finished  all  the  grain  at  hand,  a  large  '  Pouter ' 
rose,  and,  flapping  its  wings  furiously,  flew  directly  at  the  horse's 
eyes,  causing  that  animal  to  toss  his  head,  and  in  doing  so,  of 
course,  shake  out  more  corn.  I  saw  this  several  times  repeated ; 
in  fact,  whenever  the  supply  on  hand  had  been  exhausted."  The 
writer  may  well  ask  whether  this  was  not  "  something  more  than 
mere  instinct." 

The  maternal  affection  of  the  Bird  for  its  young  is  well 
known  ;  but  no  less  remarkable  is  the  Reason  which  they 
sometimes  display  under  the  promptings  of  this  Emotion. 
A  few  examples  will  illustrate  this. 

»  Aug.  21,  1873,  p.  325. 


2j0  nascent  reason,  emotion, 

White,  in  his  "  Natural  History  of  Selborne,"  says  that  somo 
riy-catchers  built  every  year  in  the  vines  that  grew  on  the  walls  of 
his  house.  "A  pair  of  these  little  birds,"  he  adds,  "had  one  year 
inadvertently  placed  their  nest  on  a  naked  bough, — perhaps  in  a 
shady  time,  not  being  aware  of  the  inconvenience  that  would  iollow: 
but  a  hot  sunny  season  coming  on  before  the  brood  was  half  fledged, 
the  reflection  of  the  wall  became  insupportable,  and  must  inevitably 
liave  destroyed  the  tender  young,  had  not  afiection  suggested  an 
expedient,  and  prompted  the  parent  birds  to  hover  over  the  nest 
all  the  hotter  hours,  while,  with  wings  expanded,  and  mouths  gaping 
for  breath,  they  screened  off"  the  heat  from  their  sufi'ering  off- 
spring." 

Another  remarkable  instance  is  also  cited  by  the  Editor  of  the 
above  work.*  He  says: — "During  a  wet  day,  a  house  swallow's 
nest  became  saturated,  and  fell  to  the  ground.  It  contained  five 
unfledged  young  ones.  A  lady  who  saw  the  accident,  collected  the 
brood,  placed  the  lining  of  the  nest  in  a  small  basket  inside  [?  out- 
side] the  window  of  her  dressing-room.  She  soon  had  the  pleasure 
of  seeing  the  old  birds  come  and  feed  their  offspring.  One  of  them 
was  so  weak,  that  it  did  not  receive  the  same  quantity  of  food  as 
the  others,  and,  consequently,  when  they  were  able  to  leave  the 
nest,  this  helpless  one  remained,  only  half  fledged,  and  suffering 
from  cold,  when  it  had  the  whole  nest  to  itself.  There  was  at  the 
time  a  bitter  north-east  wind,  which  penetrated  through  the  open- 
ings in  the  basket  work,  and  which,  of  course,  added  to  the  misery 
of  the  poor  bird.  All  at  once  the  old  ones  tvere  seen  to  come  with 
clay  in  their  mouths,  and  in  a  short  time  they  built  up  a  wall 
arfainst  the  basket,  ivhich  effectually  screened  the  young  one  from 
the  cold  ivind.     It  was  reared  and  took  its  flight.*' 

These  seem  to  be  unquestionably  reasoned  acts,  per- 
formed with  a  distinct  '  imagination  '  of  the  objects  Avhich 
they  were  to  subserve,  and  this,  too,  in  the  face  of  altogether 
unfamiliar  conditions.  We  have,  therefore,  Reason, 
Imagination,  and  Volition,  combining  for  the  attainment 
of  a  novel  end.  But  other  notable  instances  maybe  cited. 
The  Editor  of  White's  '  Selborne'  sayst:— 

♦  Bohn's  "Illustrated  Library"  edition,  p.  154. 
f  Bohn's  edition,  p.  166. 


Chap.  XV.]  IMAGINATION    AND    VOLITION.  251 

"  Several  interesting  facts  have  been  communicated  to  me  of  tlie 
revengeful  disposition  of  martins,  when  their  nests  have  been 
invaded  by  sparrows.  In.  one  instance,  at  Hamjjton  Court,  a 
gentleman  informed  me  the  morning  it  took  place,  that  a  couple 
of  sparrows  had  hatched  their  young  in  a  martin's  nest.  Two  or 
three  days  afterwards,  a  number  of  martins  came,  pecked  the  nest 
to  pieces,  and  he  saw  the  unfledged  young  dead  on  the  ground 
beneath  the  window.  In  another  instance,  the  foreman  of  the 
carpenters  at  the  palace,  Hampton  Court,  informed  me,  that  while 
working  at  his  bench  close  to  the  window,  a  pair  of  swallows  built 
their  nest  in  a  corner  of  it,  and  where  he  frequently  watched  it. 
When  completed  some  sparrows  took  possession  of  it,  and 
deposited  their  eggs.  While  the  hen  was  sitting  on  them,  several 
martins  came  and  closed  up  the  hole.  After  a  few  weeks  he  ex- 
amined the  nest,  and  found  the  bird  dead  on  her  eggs." 

Again,  according  to  Swainson,  "Many  of  the  parrot  family  are 
well  known  to  evince  a  strong  and  lasting  affection  towards  each 
other ;"  and  he  adds  : — "  Bonnet  mentions  the  mutual  affection  of  a 
pair  of  those  called  love-birds,  who  were  confined  in  the  same  cage. 
At  last,  the  female  falling  sick,  her  companion  evinced  the  strongest 
marks  of  attachment;  he  carried  all  the  food  from  the  bottom  of 
the  cage,  and  fed  her  on  her  perch ;  and  when  she  expired,  her 
unhappy  mate  went  round  and  round  her,  in  the  greatest 
agitation,  attempting  to  open  her  bill,  and  give  her  nourishment. 
He  then  gradually  languished;  and  survived  her  death  only  a  few 
months." 

But  the  actions  of  Birds  in  defence  of  their  young  are 
perhaps  the  most  remarkable,  and  associated  with  the 
greatest  strength  of  Emotion — "  self  seems  no  longer  to  be 
considered,  danger  no  more  dreaded."  As  Swainson  says  : — • 
"  The  most  feeble  birds,  at  the  season  of  incubation, 
assault  the  strong  and  fierce ;  the  weakest  will  assail  the 
most  powerful.  It  is  a  well-known  fact  that  a  pair  of 
ravens,  which  dwelt  in  a  cavity  of  the  rock  of  Gibraltar, 
would  never  suffer  a  vulture  or  eagle  to  approach  their  nest, 
but  would  drive  them  away  with  every  appearance  of  fury.'* 
And  "  the  artifices  employed  by  the  partridge,  the  lapwing, 
the  ring  plover,  the  peewit,  and  numerous  other  land  birds, 


252  NASCENT    REASON.    EMOTION, 

to  blind  the  vigilance,  and  divert  the  attention  of  those 
who  may  come  near  their  little  ones,  is  equally  curious." 

It  may  fairly  be  held  that  the  more  varied  and  complex 
the  Sensorial  Impressions  capable  of  being  discriminated 
from  one  another  (the  wider  the  range,  that  is,  of  an  ani- 
mal's Cognitive  Powers),  the  more  occasion  and  oppor- 
tunity is  there  for  elementary  modes  of  Reason  to  inter- 
vene between  ingoing  impressions  and  the  motor  responses 
which. they  are  destined  ultimately  to  incite. 

But  it  seems  clear  that,  with  the  single  exception  of 
the  sense  of  Smell,  the  sensorial  endowments  of  Birds 
are  to  be  regarded  as  far  more  developed  than  those  of 
Insects.  Their  far-reaching  and  discriminative  Vision, 
their  acute  powers  of  Hearing,  together  with  their  highly 
refined  *  sense  of  Direction,'  must  of  necessity  confer 
upon  Birds  a  power  of  increasing  enormously  the  range 
and  complexity  of  their  relations  with  the  outside  world. 
To  these  advantages  they  add  those  which  accrue  from 
their  longer  individual  lives,  and,  above  all  others,  from 
the  fact  that  these  superior  endowments  and  opportuni- 
ties of  improvement  operate  in  concert  with  a  vastly  more 
complex  Nervous  System  which  they  have  inherited  from 
a  long  but  indefinite  series  of  simpler  ancestors.  Need  we 
wonder,  then,  if  the  evidence  should  seem  to  show,  that, 
while  the  instincts  of  Birds  are  perhaps  less  elaborate, 
their  adaptive  intelligence  or  Reason,  and  the  strength 
and  definiteness  of  their  Emotions,  are  unquestionably 
far  superior  to  those  presented  by  the  Social  Insects. 

We  may,  perhaps,  safely  conclude  that,  while  many 
Instinctive  Actions  are  more  or  less  immediate  products 
or  resultants,  consequent  upon  the  undeviating  regularity 
in  the  recurrence  of  Visceral  States  and  impressions  and 
of  the  sense-guided  movements  which  they  evoke;  Reason, 


Chap.  XV. ]  IMAGINATION    AND    VOLITION.  253 

Imagination,  and  Volition,  on  the  other  hand,  as  mere 
higher  developments  arising  out  of  previous  processes, 
have  their  seed-time  in  all  that  is  unfamiliar  among  the 
chance  Sensorial  Impressions  which  Animals,  whose  '  ex- 
perience '  is  growing  and  w^hose  Nervous  Systems  are 
developing,  are  accustomed  at  intervals  to  receive  from 
the  outer  world. 


12 


CHAPTER  XYI. 

THE  BRAIN  OF  QUADRUPEDS  AND  SOME  OTHER  MAMMALS. 

A  GREAT  advance  is  to  be  met  with  in  the  cleyeloi^ment 
of  the  Brain  in  passing  from  Birds  to  Mammals,  and  from 
lower  to  higher  forms  of  the  latter.  There  are  obvious 
differences  in  external  conformation,  and  also  internal 
differences  only  to  be  detected  by  dissection  of  the 
organ. 

External  Differences. — The  first  and  most  important 
of  these  peculiarities  is  the  increasing  size  of  the 
Cerebral  Lobes  or  Hemispheres.  In  lower  Quadrupeds 
these  parts  scarcely  extend  far  enough  back  to  cover  the 
Optic  Lobes,  whilst  in  higher  terms  of  the  series  they  not 
only  hide  these  bodies  completely,  but  also  in  part  hide 
the  more  developed  Cerebellum.  The  Cerebral  Hemi- 
spheres in  Quadrupeds  also  tend  to  become  more  and 
more  plainly  indented  by  certain  primary  depressions  or 

*  fissures,'  by  which  they  are  divided  into  what  are  called 

*  lobes.'  The  Hemispheres  are  also,  to  an  increasing 
extent,  marked  by  various  smaller  secondary  fissures  or 
'sulci,'  by  which,  together  with  the  primary  fissures,  certain 
foldings  of  the  surface  of  the  brain,  known  as  *  convolu- 
tions'  or  *  gyri,'  are  produced. 

The  second  of  the  external  peculiarities,  above  referred 
to,  is  the  gradually  increasing  size  of  the  lateral  lobes  of 
the   Cerebellum—  parts  which,  like  the  Cerebral  Hemi- 


Chap.  XVI.]         THE    BRAIN    OF    QUADRUPEDS. 


255 


^® 


spheres,  will  be  found  to   attain   their  maximum  develop- 
ment in  Man. 

The  third  external  pecu- 
liarity is  a  consequence  of 
the  second.  It  consists  in 
the  gradual  increase  of  the 
'pons  Varolii/  a  part  of 
the  brain  which  stretches 
across  the  inferior  surface 
of  the  Medulla  in  a  bridge- 
like fashion.  Hence  its 
name — coupled  with  that 
of  one  of  the  earlier  ana- 
tomists. This  structure, 
which  was  formerly  believed 
to  be  merely  a  great  trans- 
verse commissure  uniting 
the  lateral  lobes  of  the  Cere- 
bellum with  one  another, 
becomes  well  developed  in 
higher  Quadrupeds  and  in 
Cetacea,  though  it  is  repre- 
sented in  Birds  only  by  a 
few  barely  perceptible  fibres. 
Its  true  nature  v/ill  be  more 
correctly  defined  in  the  de- 
scription of  the  human  brain. 

Internal  Differences. ^'*^-  68.— Brain  and  Spinal  Cord  of  Kan- 

„  .  garoo   {3Iacrop^ls).     (Owen.)    1.  Section   o 

Only   a  lew  OI    the  most   im-  Splnal  Coid  in  situation  from  winch  Nerves 

portant  and  obvious  of  these  ^^"Z!f"T'T  ^'."'^^f  V'?" 

r  tion  through  lower  dorsal  region  ;  3.  Section 

can  be  here  referred  to.              through  lumbar  swelling  of  Cord.     Each  of 

/-.    v^  rpi             •                /^    +•      t^sse   sections    shows   the   double  area  of 

[i..)  ine        two         up lilC  'grey' ganglionic  matter  within  the  Spinal 

Lobes     become     relatively  *^°^^- 

smaller  in  higher  Quadrupeds,  though  in  all  of  them  they 


256 


THE    BRAIN    OF    QUADRUPEDS    AND 


are  more  or  less  deeply  indented  in  the  transverse  direc- 
tion, by  a  depression  or  groove  which  thus  divides  them 
into  four  rounded  swellings,  answering  to  what,  in  higher 
animals  and  in  Man,  are  known  as  the  '  Corpora  Quadri- 
gemina.'  The  cavity  existing  within  them  in  lower  Verte- 
brates now  becomes  reduced  to  a  mere  passage  between 
the  third  and  fourth  Ventricles. 

(2.)  A   great    transverse    commissure,    connecting    the 
Cerebral    Lobes    with  one   another,    appears    as  a   rudi- 


PiG.  69.— Brain  of  the  Horse,  outer  surface.  (Solly,  after  Leuret.)  e,  Olfactory- 
lobe ;  h,  hipiiocampal  lobe,  or  'processus  pyriforniis.  1,  2,  3,  Lobes  of  the  Ceie- 
belluin.  o.  Optic  nerve  ;  m,  motor  occuli ;  p,  fourth  nerve  ;  t,  fifth  nerve;  u,  sixth 
nerve;/,  facial  nerve;  /,  :mditory ;  g,  glo^so-pharyngcal ;  r,  vagus;  s,  spinal- 
accessory  ;  n,  hypoglossal  nerve,     x,  Pons  Varolii 

mcntary  structure  in  lower  Quadrupeds  and  gradually 
increases  in  size  in  higher  representatives  of  this  class. 
It  is  known  as  the  Corpus  Callosum.  This  commissure 
principally  connects  the  upper  parts  of  the  Cerebral 
Lobes,  and  soon  comes  to  form  the  roof  of  the  two  great 
*  lateral  ventricles.' 

(3.)  A  double  commissure,  known  as  the  Fornix,  appears 
and  gradually  becomes  more  developed,  as  another  boundary 
of  the  'lateral   ventricles.'      Long  erroneously   described 


Ch.^p.  XVI.] 


SOME    OTHER    MAMMALS. 


257 


as  a  double  longitudinal  commissure,  its  lialves,  in  reality 
(after  a  very  irregular  course,  the  direction  of  which  varies 
in  different  animals),  connect  in  each  Cerebral  Lobe,  ipavts 
that  are  almost  situated  in  the  same  transverse  plane. 
The  nature  of  these  parts  and  the  other  relations  of  the 
Fornix  will  be  given  further  on  (p.  272),  and  also  in  the 
description  of  the  corresponding  structure  in  the  human 
brain.     Its  relations  are   of  a  complex  order,  so  that  its 


Fig.  70. 


Fig.  71. 


Ftg.  70. — ■Prain  of  Atroiiti.  (Owen.)  a,  Medulla;  6,  fourth  ventricle;  c,  median, 
and  d,  lateral  lobes  of  Cerebellum  ;  e.  Cerebral  Hemisi^here  ;  /,  olfactory  lobes 

Fig.  71. — Brain  of  Beaver.  (Owen.)  Tlie  upper  parts  of  the  Cerebral  Hemispheres 
have  been  fut  away  to  the  level  of  the  'corpus  callosum,'  so  as  to  show  this  great 
transverse  commissure,     le.  Pineal  body ;  B,  corpoia  qiiadrigemina;  C,  cerebellum. 

fuller  description  will  be  better  reserved.  It  is  necessary, 
however,  here  to  state,  that  it  mostly  lies  beneath  the 
'  Corpus  Callosum,'  and  is  closely  connected  with  this  great 
transverse  commissure  posteriorly,  though  in  passing  for- 
wards the  tv/o  structures  diverge  from  one  another. 

(4.)  In  the  space  left  between  the  Corpus  Callosum  above 


258 


THE    BRAIN    OF    QUADRUPEDS    AND 


(fig.  72,  c,  c)  and  the  diverging  Fornix  below,  are  two  thiii 
vertical  and  almost  parallel  septa.  These  septa  represent 
the  inner  walls  of  the  '  lateral  ventricles  '  and  constitute 
parts,  therefore,  of  the  contiguous  inner  faces  of  the  two 
Cerebral  Lobes.  They,  together  with  the  great  trans- 
verse commissure  above  and  the  Fornix  below,  form  the 
boundaries  of  a  narrow  and  somewhat  triangular  cavity 
known  as  the  ^  fifth  ventricle.'     This   small  ventricle  is 


Fig.  72. — Brain  of  Horse,  longitudinal  section  through  its  centre,  showing  internal 
surface  of  Cerebral  Hemisphere.  (i^oHy,  after  Lcuret.)  cc.  Corpus  callosum,  between 
it  and  the  Fornix  below  and  behind,  is  the  '  fifth  ventricle.'  p,  Thalamus;  co,  the 
middle  or  soft  commissure;  tq,  corpora  quadrigemina,  in  front  of  which  is  the 
Pineal  body,  with  one  of  its  '  peduncles  '  passing  forwards  along  the  upper  border  of 
the  corrcsi)onding  Thalamus,  and  beliind  it  the  cut  surface  of  the  middle  lobe  of 
the  Cerebellum,     e.  Olfactory  lol)e  ;  o,  olivary  body. 

quite  different  from,  and  also  quite  unconnected  with,  the 
other  four  brain  cavities,  which  are  all  of  them  continuous 
with  one  another — as  are  the  corresponding  antecedent 
cavities  met  with  in  the  early  developmental  phases  of 
the  brain.  But  the  '  fifth  ventricle '  obviously  could  not 
come  into  existence  till  the  Corpus  Callosum  and  Fornix 
had  become  developed.  Consequently  no  such  cavity 
exists  in  Birds,   Reptiles,  Amphibia,  or  Fishes.* 

*  The  arraiigenioiit  of  these  central  ]):irts  of  the  Brain  in  lower 
Quadnqx'ds  has  been  well  described  and  figured  by  Prof.  Flower 
ill  the  Philosoph.  Traus.  for  18G5. 


Chap.  XVI.  ] 


SOME    OTHER    MAMMALS, 


259 


It  must  not  be  supposed  that  anything  like  a  regular 
serial  order  or  progression  is  to  be  observed  in  the 
development  of  the  Brain  among  Mammals.  In  the 
higher  types  of  lower  orders  it  will  often  be  found 
better  developed  than  among  the  lower  types  of  higher 
orders.  Still  if  we  compare  the  extremes  of  the  class — • 
that  is,  higher  with  lower  Mammals — a  great  increase  in 
the  developmental  complexity  of  the  organ,  or  in  type  of 
Brain,  as  judged  by  the  human  standard,  will  become 
perfectly  obvious. 

The  ratio  of  the  weight  of  the  Brain  to  the  weight  of 
the  body,  is  subject  to  great  variations,  from  different 
causes,  so  that  a  table  of  such  ratios  does  not  give  any 
trustworthy  information  as  to  the  relative  development  of 
the  organ  in  different  species  of  animals.  We  may  be 
able  to  deduce  some  kind  of  rough  average,  sufficing  to 
indicate  its  increasing  development  if  we  compare  class 
with  class — as  Fishes  with  Birds,  or  Birds  with  Mammals 
— but  in  detail  and  for  estimating  the  relative  develop- 
ment of  the  Brain  in  different  species,  its  indications  are 
of  little  or  no  value.  This  may  be  illustrated  by  the 
following  table  in  which  some  of  these  ratios  are  given  : — 


Greenland  Whak 

J         .     1:3000 

Ornithorynchus 

130 

Ox       .        . 

.     1  :  860 

Porpoise 

93 

Great  Kangaroo 

.     1  :  800 

Eat      . 

76 

Wombat      . 

.     1  :  614 

Chimpanzee        , 

50 

Elephant     . 

.     1   :   500 

Man    . 

36 

Horso . 

.     1  :  400 

Field  Mouse 

31 

Sheep .         • 

.     1  :  350 

Goldfinch    . 

24 

Dog     .         .         , 

.     1  :  305 

Marmozet   . 

22 

Cat     .        .        . 

.    1  :  156 

Canary 

14 

Babbit 

Tf   la     nf  PAin 

.     1  :  140 

Blue-headed  Tit 

tIat 

nrWn 

12 

in  the  above  series  is  one  which  does  not  correspond  with 


260 


THE    BRAIN    OF    QUADRUPEDS    AND 


tlie  Intelligence  of  the  respective  creatures ;  neither  shall 
we  find  that  it  in  the  least  degree  harmonizes  with  the 
complexity  of  development  to  which  the  Brain  attains. 

One  of  the  principal  disturbing  causes  arises  from  the 
fact,  that  in  animals  of  any  given  order,  the  bulk  or 
weight  of  the  Brain  when  passing  from  its  smaller 
to  its  larger  representatives,  does  not  increase  at  all 
in  the  same  proportion  as  the  total  body- weight  of  such 
animals.  Some  striking  illustrations  of  this  fact  have 
been  cited  by  Professor  Owen.*  Small  and  large  repre- 
sentatives of  the  same  order  of  animals  are,  in  the  sub- 
joined list,  bracketed  together,  in  order  to  show  how  much 
greater  is  the  ratio  of  brain- weight  to  body- weight  in  the 
diminutive  forms. 


Very  small  Marsupial  ^ 
Great  Kangaroo 

Small  Ant-eater 
Great  Ant-eater. 

Pygmy  Chevrotain 
Giraffe 


25 
800 

60 

500 

80 
900 


Rock  Coney 
Rhinoceros 

Weazel 
Grisly  Bear 

Marmozet 
Gorilla 


:|1; 
:11: 
:!i: 


95 

764* 

90 
500 

20 

200 


In  part  explanation  of  these  very  interesting  peculiari- 
ties, Prof.  Owen  advances  the  following  hints.  "  TJie 
Brain,"  he  says,  "  grows  more  rapidly  than  the  body,  and 
is   larger   in   proportion    thereto  -at    birth    than    at   full 

growth So    in    the   degree    in    which   a    species 

retains  the  immature  character  of  dwarfishuess,  the  brain 
is  relatively  larger  than  the  body."  This  may  be  to  some 
extent  an  explanation  of  the  peculiarity  above  shown  to 
exist ;  but  there  are,  doubtless,  other  vital  and  mechanical 
reasons,  why  the  bulk  of  the  Brain  should  not  increase 
quite  proportionately  with  the  bulk  of  the  body. 

We  may  now  point  out  some  of  the  more  striking  pecu- 
*  "Anat.  of  the  Vertebrates,"  iii.  p.  143. 


Chap.  XVI.] 


SOME    OTHER    MAMMALS. 


261 


liarities  of  the  several  parts  of  the  Bram,  as  met  with  in 
different  representatives  of  the  great  class  of  Quadrupeds. 

The  Medulla,  the  Cerebellum,  and  the  pons  Varolii, 
are  so  intimately  related  to  one  another,  hotli  struc- 
turally and  functionally,  that  they  may  here  be  regarded 
as  constituting  one  compound  division  of  the  Brain. 

There  is  nothing  special  to  be  said  concerning  the 
Medulla  in  Quadrupeds,  except  that 
the  lateral  projections,  known  as  '  oli- 
vary bodies,'  gradually  become  more 
developed  (fig,  72,  o).  In  many  ani- 
mals, a  layer  of  fibres  on  each  side, 
known  as  the  '  corpus  trapezoideum ' 
(fig.  73),  crosses  these  structures  and 
partially  hides  them.  In  higher  Quad- 
rupeds, however,  such  transverse  fibres 
cross  the  Medulla  at  a  higher  level  or 
appear  to  be  absent  (fig.  74).  Where 
this  is  the  case  the  *  olivary  bodies  '  are 
uncovered ;  and  as  they  also  become 
larger,  they  may  form  rounded  promi-  fig.  73.-Brain  of  Rabbit, 
nences,  one  on  each  side  of  the  Medulla.  ^^Tt  oifa'S'  loS; 

The  above-mentioned '  corpora  trape-  i,  Lobe  of  the  Hippocampus, 
zoidea,'  usually  cross  the  Medulla  at  the  ^|  opt^kj^'^ner^'veTwr  motor 
level  of  the  '  origin '  of  the  auditory  and  f'^cuu ;  c  m,  corpus  mammii- 

^  T      •  ^^^^  '  P  ^'  ^^^'^  cerebri ;  p  v, 

facial  nerves.     They  are  very  distmct  pons  varolii;  bt  corpus  tra- 
in  the  Lion,  the  Dog,  and  the  Sheep.*  ^^:,.,  ^J^! 

The  upper  part  of  the  Medulla  is 
bridged  above  and  closely  embraced  by  a  much  thicker 
mass  of  fibres  known  as  the  pons  Varolii,  the  develop- 
ment of  which  in  different  Mammals,  is  found  to  be  strictly 
proportionate  to  the  development  of  the  lateral  lobes  of 
the   Cerebellum. 

*  See  Tiedemann's  'Icones  Cerebri  Siniiarura,'  Tab.  iii.  and  vii. 


262 


THE    BRAIN    OF    QUADRUPEDS    AND 


Where  the  Pons  is  well  developed,  the  '  cerebral  pedun- 
cles,' being  more  covered,  appear  to  be  curtailed  in 
length  (fig.  74,  i,  i). 

The  Cerebellum  in  Marsupials  (fig.  68),  still  consists 
principally  of  the  '  median  lobe,'  the  surface  of  which  is 
marked  by  deep  transverse  fissures,  giving  rise  to  a  series 
of  nearly  parallel  convolutions.     Its  '  lateral  lobes  '  exist 


Pig.  74.— Brain  of  Dolphin,  under  surface.  (Owen,  after  Tiedemann.)  a.  Spinal 
cord  ;  b,  anterior  pyramids  ;  c,  Pons  Varolii ;  e,  posterior  inferior  lobe  of  Ctrobolluni; 
f,  anterior  inferior  lobe,  g,  amygdaloid  lobe,  and  //,  flocculus,  all  lobes  of  Cerebellum. 
i,  ?,  Cerebal  ])eduncles;  p,  corpus  albicans;  o,  pituitary  boviy ;  m,  temporal  lobe, 
and  /,  anterior  lobo  of  Cerebrum.  Olfactory  bulbs  absent ;  2.  optic  nerves  ;  3,  motor 
nerves  of  eyes  (fourth  nerve  apj^ears  from  above  the  Cereliellum,  in  front  of  ;/)  ; 
5,  the  trigeminus ;  6,  the  sixth  nerve ;  7,  the  facial,  and  8,  the  auditory  nerves ; 
9,'glosso-pharyngeal ;  10,  vagus  ;  11,  spinal  accessory;  12,  hypoglossal;  13,  first  cervical 
nerve. 

merely  as  small  appendages,  and  are  tliought  by  some 
anatomists  to  correspond  in  higher  forms  with  certain 
accessory  lobules,  named  '  flocculi.'  Among  Rodentia  the 
lateral  lobes  show  a  marked  increase  in  size,  which  is 
obvious  in  the  Hare  (fig.  76),  and  still  more  so  in  the 
Beaver   (fig.   71)   where  these  parts   arc  distinctly  larger 


Chap.  XVI.] 


SOME    OTHER    MAMMALS. 


263 


than  the  median  lobe.  In  Solipecles,  Kuminants,  and 
Carnivores,  the  lateral  lobes  also  begin  to  surpass  the 
median  in  size.  This  increase  is  very  notable  among  the 
latter  in  the  Cat  (fig.  79),  and  also  in  the  Dog  (fig.  80)  ; 
but  it  is  still  more  marked  in  many  Cetacea,  such  as  the 
Dolphin  (fig.  74),  and  the  Porpoise  (fig.  77). 


Fig.  75. 


Fig.  76. 


Fig.  7.5.— Brain  of  the  Horse,  upper  aspect.     (Owen.) 
Fig.  76. — Brain  of   the  Hare,  upper  aspect.      (Spurzheirn.) 
b,  Cerebral  Hemispheres  ;  d,  CerebeUum  ;  e,  Medulla. 


Olfactory  lobes; 


In  some  Solipedes  and  Carnivores,  the  Cerebellum, 
instead  of  consisting  of  broad  and  comparatively  smooth 
lateral  lobes,  together  with  a  narrower  and  much  divided 
median  portion  (fig.  77),  is,  as  Marshall  says,*  "  very 
uneven  upon  its  surface,  apparently  consisting  of  a 
*  "  Outlines  of  Physiology,"  vol.  i.  p.  414. 


'264 


THE    BRAIN    OF    QUADRUPEDS    AND 


cluster  of  many  irregular  and  deepl}^  foliated  lobules." 
This  kind  of  conformation  is  represented  in  fig.  75.  In 
the  marvellously  active  Bat,  the  Cerebellum  is  very  large 
in  proportion  to  the  size  of  the  Cerebral  Lobes — though 
in  this  animal  it  seems  to  be  tiie  median  portion  which 
becomes  so  highly  developed  (fig.  78). 

Between  the  under  surface  of  the  median  lobe  of  the 

Cerebellum 
and  the  back 
of  the  Medul- 
la, there  is  a 
small  lozenge- 
shaped  space, 
known  as  the 
*  fourth  ven- 
tricle,' formed 
by  the  diver- 
gence of  what 
were  the  pos- 
terior columns 
of  the  Spinal 
Cord,  and  the 
consequent 
opening  up 
of  its  central 
canal.  The 
lower  extremity  of  this  space  may  be  seen  in  figs.  79,  80. 
The  size  of  the  Optic  Lobes,  in  proportion  to  the  rest 
of  the  Brain,  is  very  much  less  in  Quadrupeds  than  it  is 
in  Birds,  and  this  ratio  goes  on  diminishing  as  we  pass 
from  lower  to  higher  representatives  of  the  former  class. 
These  bodies  have  a  greater  proportional  size  in  Marsupials 
and  Eodents,  for  instance,  than  in  Kuminants  and  Carni- 
vores.    The  cavities  to  be  fo^ind  in  their  interior  in  Birds 


Fin.  77.— Brain  of  the  PorpoLsc,  with  tlie  upper  half  of  the 
left  Hemisphere  cut  away  so  as  to  show  the  contents  of  the 
Lateral  Ventricle.  (Solly.)  1,  Outer  wall  of  Ventricle  ;  2,  Corpus 
Btriatum  ;  3,  Fornix ;  4,  5,  anterior  and  j^osterior  segments 
of  quadrigerninal  bodies  ;  0,  corpus  callosuni  ;  7,  Cerebellum ; 
8,  Spinal  Cord  ;  0,  Pineal  body. 


Chap.  XVL]  SOME    OTHER    MAMMALS.  265 

and  lower  Vertebrates  have  almost  ceased  to  exist.  The 
transverse  depression  which  divides  the  two  bodies  into 
four  ('  corpora  quadrigemina  '),  though  present  in  all  Quad- 
rupeds, divides  them  variously.  Thus  in  nearly  all  the 
lower  classes,  as  well  as  in  most  Rumi- 
nants and  Solipedes,  the  anterior  segments 
are  larger  than  the  posterior  (fig.  81) ; 
while  in  Carnivora  and  in  some  of  the 
Cetacea,  such  as  the  Porpoise  (fig.  77),  the  ,/^^  78.--Brain  of 

'  ^  V    o      •     /'  the  Bat,  side  view. 

posterior  segments  are  usually  the  larger.  (Soiiy.)  a,  olfactory 

T  rk        J  J       1  ^.^  X      •        lobe ;     b,     Cerebral 

In  many  Quadrupeds,  however,  the  anterior  Hemisphere ;  e,  ce- 
and  the  posterior  segments  are  nearly  equal  rebeiium;  h,  spinai 
in  size.  The  degree  of  development  of  the 
posterior  segments  seems  to  be  often  in  accordance  with 
that  of  the  Cerebellum  with  which  they  are  in  clos3 
structural  connection. 

Fig.  79.  Fig.  80. 


Fig.  79.— Cerebellum  of  the  Cat,  upper  and  posterior  aspect.     (Ferrier.) 
Fig.  80.— Cerebellum  of  the  Dog,  upper  and  posterior  aspect.     (Ferrier.) 

The  Cerebral  Hemispheres,  narrowed  in  front,  are 
more  or  less  elongated  and  ovoid  in  form — except  in  Seals, 
Porpoises  and  Dolphins  (figs.  77,  101),  in  which  the 
transverse  diameter  of  these  segments  may  even  exceed 
the  longitudinal.  They  are  relatively  small  in  the  lower 
orders  of   Quadrupeds,  as  may  be  seen  from  the  figure 


266 


THE    BRAIN    OF    QUADRUPEDS    AND 


of  the  brain  of  the  Kangaroo  (fig.  68),  together  with 
those  of  the  Hare  and  the  Squirrel  (figs.  76,  82).  In 
these  animals  they  leave  the  '  olfactory  lobes '  more  or 
less  uncovered  in  front,  and  sometimes  the  *  corpora 
quadrigemina '  in  the  same  condition  behind.  But  in 
Kuminants,  Solipedes  and  Carnivores  (figs.  94,  72,  87)  the 
Cerebral  Lobes  increase  in  size,  so  as  not  only  to  cover 
the  before-named  bodies  in  front  and 
behind,  but  also  in  part  to  overlap  the 
Cerebellum. 

In  the  Seal,  the  Porpoise  and  the 
Dolphin  (figs.  77,  101),  the  Cerebral 
Hemispheres  undergo  a  still  more 
marked  increase  in  size.  In  these  ani- 
mals, also,  as  well  as  in  Quadrumana 
and  Man,  we  no  longer  find  a  distinct 
^  pyriform  process/  recognizable  as  a 
part  of  each  '  temporal  lobe  '  at  its 
Fig.   81.— Brain   of    the  under  and  inner  surface — such  as  exists 

Squirrel,  Hemisphei-es  scpa-  .       ,-,  •       • ,  o    J^         i  r  r 

rated  so  as  to  expose  iho  ^  the  majority  ol  thc  lowcr  terms  oi 

great  basal  gau-lia.     (Solly.)  Quadrupeds. 

E,   Cerebral  hcniispbere ;   k,  ■'■  ^ 

Cerebellum  ;  M,  Corpus  stria-         TllCSC   bodicS,   wllicll    liaVO  alsO  1)0011 

tam;  K,  ihaiamus;  c,  ^>  named  '  hippocaiiipal  lobos,' are  merely 

Cori)ora  quaurigeuiina.  i  r  i  '  >' 

the  lowest  portions  of  the  Tempoi-al 
Lobes  more  or  less  separated  from  the  remainder  by  a 
superficial  depression.  The  continuity  existing  botweon 
the  Olfactory  Peduncles  and  these  parts  of  the  brain  is 
particularly  well  marked  in  the  Red  Coatimondi,  the 
Agouti,  the  Porcupine  and  thc  Water  Kat,  as  ma}^  be  seen 
from  the  figures  given  by  Tiedomann.  This  connection 
is  also  indicated  by  our  figs.  69,  73,  82,  93  and  9-1. 

These  *i^yriform  processes'  arc  hollowed  l)y  spurs  of 
tlic  lateral  ventricles.  In  the  animals  in  which  they  are 
well  marked,  the  Olfactory  Peduncles  and  Lobes  are  like- 


Chap.  XVI.] 


SOME    OTHER    MAMMALS. 


2G7 


wise  well  developed  hollow  structures,  as  they  are  in  many 
Keptiles.  The  size  of  the  '  pyriform  processes  '  in  Quad- 
rupeds is,  in  fact,  generally  in  direct  relation  with  that 
of  the  Olfactory  Lobes,  and  these  are  especially  well 
developed  in  Eodents,  Euminants,  and  certain  Carnivores, 
while  they  are  ab- 
sent altogether  in 
some  of  the  Ce- 
tacea  (fig.  74). 

The  more  mi- 
nute   description  c 
of    the     external 
surface     of     the 

Cerebral        Hemi-      Fig.S2.  -Head  and  brain  of  caSquirrel,  side  view.  (Solly.) 
,  .       A,  Olfactoiylobe;  b,  Cercbr  il  hemisphere  ;  e.  Cerebellum  ; 

spheres,  compris-  h,  spinai  cord. 
ing  some  account 

of  their  *  fissures,'  'lobes,'  and  'convolutions,'  may  for 
the  moment  be  deferred,  till  we  have  first  given  some 
attention  to  the  Ventricles,  Commissures,  and  other  inter- 
nal parts  of  the  Brain. 


Internal   Topography   of  the   Brain   in    Quadrupeds 
and    some    other    Mammals. 

Each  Cerebral  Lobe  or  Hemisphere  contains  a  Lateral 
Ventricle,  the  size  and  shape  of  which  is  very  variable — 
these  being  in  great  part  dependent  upon  the  general 
form  of  the  Hemispheres,  and  upon  the  relative  size  and 
shape  of  the  ganglionic  prominences  which  the  Ventricles 
contain.  As  already  mentioned,  in  Quadrupeds  possessing 
very  large  Olfactory  Lobes,  prolongations  of  the  Lateral 
Ventricles  extend  into  them  through  their  '  peduncles,' 
from  those  spurs  which  stretch  downwards  into  the  corre- 
spondingly developed  '  pyriform  processes.' 


268 


THE    BRAIN    OF    QUADRUPEDS    AND 


At  the  anterior  part  of  the  floor  of  each  Lateral  Ven- 
tricle, is  the  rounded  prominence  known  as  the  Corpus 
Striatum.  These  bodies  vary  much  in  size  in  animals  of 
different  orders.  Thej  are  small  in  Marsupials,  and  are 
in  them  partly  overlapped  by  another  well- developed  pro- 
jection known  as  the  Hippocampus  Major — a  body 
corresponding  with,  and  produced  by,  a  deep  depression 


Fig.  83. 


Fig.  84. 


Fig.  85. 


Fig.  83.— Brain  of  a  Chelonian.    Fig.  84.— Brain  of  a  Foetal  Calf.     Fig  85.- Brain  of 

a  Cat. 
These  three  figures,  from  Gegenbauer,  ilhistrate  the  comparative  development  of 
the  Cerebral  Hemispheres  and  related  parts.  In  Figs.  83,  84,  the  roof  of  the  Lateral 
Ventricle  is  removed  on  the  left,  and  the  Fornix  and  Hippocampus  also  on  the  riglit. 
In  Fig.  85  the  whole  lateral  and  posterior  portions  of  the  riijht  Hemisphere  are 
removed,  and  as  much  on  the  left  as  is  necessary  to  display  tlie  upward  bend  of 
the  Hippocampus.  In  all  the  figures  I  m.arks  the  Cerebral  Hcnusphcre  ;  II,  the 
1halain\is;  111,  the  Corpora  Quadrigemina  ;  IV,  Tlie 'Cerebellum  ;  V,  the  Medulla. 
ol.  Olfactory  lobe  (shown  in  Fig.  83  as  conmumicating  with  the  Lateral  Ventricle) ; 
s  t,  Corpus  Striatum  ;  /,  Fornix  ;  /(,  Hippocampus  ;  sr,  fourth  ventricle  ;  (j,  geniculate 
body. 


or  fissure  on  the  inner  surface  of  the  Hemisphere — the 
*  fissure  of  the  Hippocampus.'  In  Hares  also  tlie  Cor- 
pora Sti-iata  are  small,  while  the  Hippocampi  are  large. 
The  latter  bodies  are 


remarkable   for  their  great  size  in 


Chap.  XVI.] 


SOME    OTHER   MAMMALS. 


269 


the  Beaver.  The  Corpora  Striata  are  said,  by  Stannius, 
to  be  large  in  Bats,  in  many  Rodents,  and  also  in  the 
Edentata. 

Contiguous  and  posterior  to  each  Corpus  Striatum  is 
another  rounded  eminence,  sometimes  called  the  '  Optic 
Thalamus,'  but  which  it  will  be  far  better  simply  to 
term  the  Thalamus.     These  bodies  have  previously  been 


Fio.  86.— The  Brain  of  the  Dolphin,  with  the  upper  part  of  the  Hemispheres  cut  off 
—above  the  level  of  the  Ventricle  on  the  left,  and  so  as  to  show  this  cavity  on  the 
right  side.  (Owen,  after  Tiedemann.)  b,  Corpus  callosum  ;  c,  c,  bottom  of  surface 
fissures  or  'sulci;'  d,  k,  Corpus  Striatum;  h.  Hippocampus,  with  its  unusually 
bioad  free  border  or  '  toenia  '  (i)  continued  into  the  Fornix  ;  g,  Thalamus. 

referred  to  in  Reptiles  and  Birds,  where  they  first  show 
themselves  as  projections  developing  from  the  upper  and 
inner  aspects  of  the  Cerebral  Peduncles  :  in  Quadrupeds, 
however,  owing  to  the  backward  extension  of  the  Cerebral 
Hemispheres,  they  seem  to  become  included  within  these 
and  to  project  into  the  inner  part  of  the  floor  of  each 
Lateral  Ventricle.  But  in  reality  they  lie  outside  these 
parts.  They  are  overlapped  by  the  '  velum  interpositum,' 
a  membrane  constituting  the  roof  of  the  Third  Ventricle. 


270 


THE    BRAIN    OF    QUADRUPEDS    AND 


and   also   by  the  *  fornix  '  and   '  lyra/  tlie   description  of 
which  will  shortly  follow.* 

Between  the  contiguous  inner  surfaces  of  the  Thalami 


Fig.  87.— The  Cerebral  Hemispheres  of  the  Dog,  separ.ited,  after  division  of  the 
Corpus  Callosum,  so  as  to  expose  the  Ventricles  and  Basal  Ganglia.  (Fen-icr.) 
1,  Internal  surface  of  left  Hemisphere  ;  2,  Corpus  Striatum  ;  3,  Thalamus  ;  4,  5, 
corpora  quadrigemina  ;  G,  anterior  pillar  of  the  fornix,  divided  on  tlic  left,  undivided 
on  the  right  side  (12) ;  7,  the  third  ventricle,  exposed  by  drawing  the  thalami 
asunder;  8,  the  upper  surface  of  the  Cerebellum;  9,  olfactory  lobe  or  bulb;  10, 
anterior  commissure  ;  11,  corpus  callosum,  divided ;  13,  middle  commissure,  ex- 
tending across  the  third  ventricle  ;  14,  pineal  body,  lying  over  and  concealing  the 
posterior  commissure  ;  15,  descending  cornu  of  the  lateral  ventricle. 

there  is  a  narrow  space  known  as  the  Third  Ventricle 
(figs.  72,  p;  87,  7).  It  is  situated  below  the  level  of  the 
Lateral   Ventricles,    though  each  of  these  opens  into  it 

*  By  reference  to  fig.  87,  it  will  be  seen  that  the  fornix  (12) 
constitutes  the  inner  and  posterior  boundary  of  the  Cerebral 
Hemisphere,  and  that  the  Thalamus  (3)  Hes  quite  outside  it  and 
its  Ventricle — though  the  inspection  of  a  horizontal  section  of 
the  hemisphere,  as  in  fig.  86,  might  give  rise  to  an  entirely  opposite 
impression. 


Chap.  XVI.]  SOME    OTHER    MAMMALS.  271 

anteriorly  through  the  *  foramen  of  Monro.*  Behind,  it 
is  continuous  by  means  of  a  passage  beneath  the  Corpora 
Quadrigemina  (fig.  72,  t  q)  with  the  Fourth  Ventricle.  The 
Third  Ventricle  is  likewise  continuous  below  with  the 
*  infundibulum  '  of  the  Pituitary  Body.  At  its  posterior 
and  upper  boundary  is  the  peculiar  pyriform  structure 
known  as  the  Pineal  Body,  which  is  attached  by  two  long 
peduncles  to  the  upper  and  inner  borders  of  the  Thalami 
(fig.  72).  This  body  itself  lies  against  and  just  in  front 
of  the  Corpora  Quadrigemina;  it  is,  in  proportion  to 
other  parts,  decidedly  smaller  than  the  corresponding 
structures  in  Keptiles  or  Birds.  It  is  extremely  small  in 
the  Eabbit  and  some  other  Eodents. 

The  distinct  Commissures  seen  in  or  in  connection  with 
the  Lateral  and  Third  Ventricles  are  five  in  number.  Of 
these,  three  are  to  be  found  also  (though  in  a  very 
rudimentary  condition)  in  some  of  the  lower  Vertebrates, 
while  the  two  others  appear  for  the  first  time  in  Quadru- 
peds. 

The  Anterior  Commissure  is  a  band  of  fibres  of  vari- 
able thickness,  which  stretches  across  the  anterior  and 
upper  boundary  of  the  Third  Ventricle  (fig.  87,  10),  and 
penetrates  deeply  through  each  Corpus  Striatum  to  certain 
surface  regions  of  the  Cerebral  Hemispheres.  It  is  larger 
in  Marsupials  and  Monotremes  than  in  any  other  Mam- 
mals, and  in  higher  representatives  of  the  class  it  is 
usually  thickest  in  those  animals  which  have  well-developed 
Olfactory  Lobes,  since  it  seems  to  be  a  commissure  serving 
principally  to  bring  the  two  cerebral  centres  of  the  sense 
of  Smell  into  relation  with  one  another.  In  part  it  con- 
nects the  Olfactory  Peduncles  with  one  another,  an  din  part 
it  serves  to  bring  into  relation  those  regions  of  the  brain  in 
each  hemisphere  in  and  about  the  Hippocampi,  to  which 


272      THE  BRAIN  OF  QUADRUPEDS  AND 

the  majority  of  the  root  fibres  of  such  tracts  proceed.  It 
is  a  structure,  therefore,  much  larger  in  the  greater  num- 
ber of  Quadrupeds  than  it  is  in  Man.  In  some  of  the 
Cetacea  the  '  anterior  commissure  '  is  so  small  as  to  be 
almost  non-existent. 

The  Middle  Commissure  is  a  short  and  rather  thick 
bridge  of  soft  ganglionic  matter,  which  passes  across  the 
middle  of  the  Third  Yentricle  (figs.  87,  13;  72,  co)  from 
one  thalamus  to  the  other,  and  therefore  serves  to  connect 
these  two  great  ganglia. 

The  Posterior  Commissure  is  small,  and  composed  of 
white  fibres.  It  passes  immediately  in  front  of  the  base 
of  the  Pineal  body,  and  its  fibres  are  prolonged,  on  each 
side,  into  the  substance  of  the  posterior  part  of  the  Tha- 
lamus. 

We  come  now  to  the  commissures  met  with  only  in  the 
brain  of  Mammals. 

The  Fornix  is  a  double  commissure,  each  half  of  which 
suffices  to  connect  two  regions  of  the  same  Hemisphere 
with  one  another — viz.,  the  Hippocampal  region  with  the 
inner  part  of  the  corresponding  Thalamus.  The  two 
halves  of  this  structure  come  into  contact  only  during  a 
small  part  of  their  course — about  the  middle  of  it — but 
they  are  also  brought  into  some  sort  of  relation  posterior 
to  this  point  by  means  of  a  stratum  of  cross  fibres,  the 
nature  and  connections  of  which  are  described  below. 

Along  the  inner  side  of  the  Hippocampus,  as  it  projects 
into  the  descending  prolongation  of  the  Lateral  Ventricle, 
a  ridge  or  band  of  white  fibres  ('  tenia  hippocampi ')  may  bo 
traced  upwards  on  each  side  (fig.  86,  i),  which  soon  becomes 
free  as  the  '  posterior  pillar '  of  the  Fornix,  and  bends  for- 
wards and  inwards  over  the  Thalamus  so  as  to  join  its 
fellow  on  the  opposite  side,  as  above  stated.  Posterior  to  the 
point  of  contact  of  these  '  pillars  '  with  one  another,  certain 


CuAP.  XVI.l  SOME    OTHER   MAMMALS.  273 

transverse  fibres  (known  as  *  psalterial  fibres  ')  exist,  which 
form  a  reflected  part  of  the  great  transverse  commissure  or 
Corpus  Callosum.  This  body  is,  in  fact,  bent  upon  itself 
behind,  and  it  is  the  portion  (thence  prolonged  forwards  to 
the  posterior  pillars  of  the  Fornix,  somewhat  triangular 
in  shape)  which,  in  higher  Mammals,  is  commonly  called 
the  '  psalterium '  or  '  lyra.'  Beneath  it  is  a  membrane 
('  velum  interpositum ')  tying  on  the  surface  of  the 
Thalami  (a  great  part  of  which  it  hides),  and  forming 
a  kind  of  roof  over  the  Third  Ventricle. 

Opposite  the  anterior  extremities  of  the  Thalami,  the 
two  halves  of  the  Fornix  again  separate  so  as  to  constitute 
its  'anterior  pillars,'  which  dip  downwards  just  behind 
t-he  Anterior  Commissure,  along  the  side  of  the  third 
ventricle  to  its  floor,  where  each,  after  twisting  upon  itself, 
so  as,  with  its  fellow,  to  cause  a  single  white  projection 
'  Corpus  albicans ')  near  the  centre  of  the  base  of  the 
brain  (fig.  74,  p),  again  passes  upwards  and  penetrates  the 
inner  side  of  the  corresponding  Thalamus. 

The  Fornix  exists  in  all  Quadrupeds,  and  has  a  much 
larger  relative  size  in  some  of  the  lower  forms  than  in  the 
Quadrumana  or  Man.  It  is,  for  instance,  extremely  well 
developed  in  the  Beaver,  the  Eabbit,  and  other  Rodents. 

The  Corpus  Callosura  was  formerly  believed  not  to 
exist  in  the  Monotremes  and  Marsupials ;  and,  in  fact,  it 
is  present  in  them  only  as  a  very  rudimentary  structure. 
Tn  Insectivora  it  is  larger ;  while  in  some  Rodents  it  has 
already  attained  a  considerable  development,  as  may  be 
seen  from  the  brain  of  the  Beaver  (fig.  71),  where  it  is 
thick  and  comparatively  long  from  before  backwards.  In 
this  animal  it  has  also  attained  the  more  horizontal  direc- 
tion commonly  met  with  in  higher  forms,  though  in  some 
other  Rodents  it  is  a  notably  less  developed  structure — 
being  short,  thin,  and  nearly  verticaWn  direction.     The 


274  THE    BRAIN    OF    QUADRUPEDS    AND 

figures  show  a  more  developed  form  of  the  Corpus  Cal- 
losum  in  the  Horse  (fig.  72),  in  the  Dolphin  (fig.  85),  and 
in  the  Dog  (fig.  87). 

The  Corpus  Callosum  stretches  across  from  one  Cere- 
bral Hemisphere  to  the  other ;  its  fibres  constitute  the 
roof  of  each  Lateral  Ventricle,  and  thence  diverge  to  many 
parts  of  the  surface  grey  matter  of  each  Hemisphere. 
Similar  cortical  areas  on  the  two  sides  are  thus  brought 
into  functional  relation  with  one  another.  It  has,  therefore, 
a  wider  kind  of  office,  though  identical  in  nature  to  that 
performed  by  the  Anterior  Commissure.  It  is  an  error, 
however,  to  place  these  structures  in  the  same  category 
with  the  Fornix,  as  many  of  the  older  anatomists  and 
even  some  modern  writers  have  done — since  this  latter 
commissure  serves  to  unite  difi'erent  regions  of  the  same 
Hemisphere,  rather  than  similar  regions  of  the  two 
Hemispheres  with  one  another. 

The  mode  in  which  the  Corpus  Callosum  and  the  Fornix 
are  united  posteriorly  by  the  *  psalterial  fibres,'  and  the 
way  in  which  the  same  two  bodies  recede  from  one  another 
anteriorly,  and  thus  contribute  to  the  formation  of  the 
Fifth  Ventricle,  has  been  previously  described  {see  also 
fig.  72). 

Any  one  wishing  to  obtain  more  distinct  notions  as  to 
the  varying  developments  and  relations  of  these  several 
Commissures,  should  consult  the  admirable  figures 
given  by  Flower,*  illustrating  the  relative  size  and  dis- 
tribution of  these  parts  in  the  Sheep,  Eabbit,  Sloth,  and 
Hedgehog,  as  compared  with  what  obtains  among  certain 
Marsupials  and  Monotremes. 

*  Philosoph.  Traus.  1865,  PI.  xxxvii.  aud  xxxYiii. 


Caav.  XVI.]  SOME    OTHER    MAMMALS.  275 


External  Topography  of  the  Brain  in  Quadrupeds, 
and  some   other  Mammals. 

The  thickness  of  the  layer  of  ganglionic  Grey  Matter 
on  the  surface  of  the  brain  undergoes  a  gradual  increase 
among  the  Yertebrata.  The  layer  is  so  thin  in  Fishes 
that  the  surface  of  the  Cerebral  Lobes  appears  almost 
white  to  the  naked  eye.  In  Mammals,  however,  we  have, 
even  in  the  lowest  of  them  (and  its  thickness  increases  in 
higher  forms)  a  continuous  stratum  of  such  matter  cover- 
ing the  whole  of  the  Cerebral  Hemispheres.  Of  course 
the  more  the  surface  of  the  hemisphere  is  folded  and  con- 
voluted, the  greater  is  its  proportional  amount,  since  this 
Grey  Matter  covers  all  parts  of  the  surface,  whether  it  Le 
folded  inwards  or  outwards  (fig.  85,  c,  c). 

In  Fishes,  Amphibia,  Reptiles,  and  Birds,  there  are  no 
regular 'fissures,'  and,  consequently,  no  division  of  the  Cere- 
brum into  *  lobes. '  Each  Cerebral  Hemisphere  has,  indeed, 
in  these  lower  forms  been  supposed  by  some,  though  on 
insufficient  grounds,  to  correspond  with  the  *  anterior  lobe ' 
of  the  brain  of  the  Ape  and  Man.  The  *  middle  lobes ' 
are  believed  to  make  their  appearance  subsequently,  as 
added  parts,  in  the  lower  Quadrupeds ;  while  the  '  pos- 
terior lobes  '  are,  similarly,  deemed  to  make  their  first 
appearance  among  the  lower  Quadrumana.  But,  as  Prof. 
Marshall  very  properly  observes,  **  the  lobes  may  not  be 
distinguishable,  and  yet  homologous  parts  of  the  cerebral 
hemispheres  may  be  present,  however  slightly  developed, 
throughout  all  the  Vertebrates.*'  The  appearance,  indeed, 
of  the  brain  of  some  of  the  Cetacea,  such  as  the  Porpoise 
and  the  Dolphin,  makes  it  rather  more  probable  that  it  is  the 
middle  regions  of  the  brain  which  are  specially  developed 
in  them,    while  both   anterior  and   posterior  lobes  (and 


276      THE  BRAIN  OF  QUADRUPEDS  AND 

especially  the  latter)  are  in  a  comparatively  rudimentary 
condition. 

Speaking  generally,  it  may  be  said  that  in  Quadrupeds 
the  Brain  tends  gradually  to  become  more  and  more  con- 
voluted as  we  proceed  from  lower  to  higher  orders.  It 
must  not  be  supposed,  however,  that  anything  like  a 
serial  development  is  to  be  detected — in  the  first  place, 
because  certain  differences  in  *  plan  of  Convolution,'  seem  to 
be  traceable  among  them  ;  and  secondly,  because  in  all  the 
orders  (and  therefore,  even  in  cases  where  the  same  plan 
is  observable),  the  degree  of  complicacy  of  the  convolutions 
is  very  largely  determined  by  the  mere  size  of  the  animal. 
It  has  been  found,  for  instance,  as  a  general  rule  to  which 
there  are  only  few  exceptions,  that  in  animals  of  the  same 
group  or  order,  the  number  and  complexity  of  the  convolu- 
tions increase  with  the  size  of  the  animal.  This  may  be 
recognized,  for  instance,  by  a  comparison  of  the  brain  of  the 
Horse  with  that  of  the  Elephant ;  of  those  of  the  Sheep 
and  Ox  ;  of  the  brain  of  the  Cat  with  that  of  the  Seal ; 
and  also,  as  we  shall  find,  of  those  of  smaller  and  of 
larger  Quadramana.  In  the  Elephant,  the  largest  though 
also  the  most  sagacious  of  existing  Quadrupeds,  the  com- 
plexity of  cerebral  convolutions  is  at  its  maximum.  They 
are  also  exceedingly  complex  in  the  huge  Cetacea,  and 
even  in  some  of  the  smaller  representatives  of  the  same 
class. 

It  has  been  previously  shown  that  the  weight  of  the 
Brain  as  compared  with  that  of  the  body  is  less  in  different 
orders  of  animals,  as  the  size  of  the  representative  of  any 
such  order  increases  ;  yet  now  it  appears  that  this  smaller 
proportional  size  of  the  Brain  in  large  animals  is,  to  a 
certain  extent,  compensated  by  its  greater  proportional 
extent  of  surface  ganglionic  matter — obtained  through 
increased  number  and  depth  of  Convolutions. 


Chap.  XVI.]  SOME    OTHER    MAMMALS.  277 

There  cannot  therefore  be,  among  animals  of  the  same 
order,  any  simple  or  delinite  relation  between  the  degree 
of  the  Intelligence  of  the  creature  and  the  numler  or 
disposition  of  its  Cerebral  Convolutions — since  this  struc- 
tural feature  of  the  Brain  seems  to  be  most  powerfully 
regulated  by  the  mere  bulk  of  the  creature  to  which  it 
belongs.  But  if,  when  taken  alone,  the  degree  of  com- 
plicacy of  the  convolutions  affords  no  safe  guidance  in 
regard  to  the  degree  of  an  animal's  Intelligence,  when 
comparing  different  species  of  the  same  order  (whose 
convolution al  '  pattern  '  is  therefore  the  same),  it  will  be 
found  to  fail  even  more,  as  a  criterion  for  estimating  the 
relative  Intelligence  of  representatives  of  different  natural 
orders — especially  if  these  should  happen  to  be  orders 
characterized  by  a  different  convolutional  'pattern.'  Thus, 
the  brain  of  the  Beaver  is  almost  smooth,  while  that  of 
the  Slieep  presents  numerous  convolutions  which  both  in 
number  and  complexity  decidedly  surpass  even  those  of 
the  Dog. 

The  more  closely  animals  are  related  to  one  another, 
however,  and  the  more  they  are  of  about  the  same  size, 
the  more  should  we  be  entitled  to  look  for  some  propor- 
tional relations  between  the  development  of  their  Cerebral 
Convolutions  and  their  Intelligence.  The  comparison  of 
convolutional  complexity  is  therefore  of  principal  interest 
and  value  when  we  are  concerned  with  species  of  the  same 
or  closely  allied  orders,  or,  even  more,  when  we  compare 
the  Brains  of  individuals  of  the  same  species,  or  of  mere 
varieties,  with  one  another.  This  kind  of  interest,  there- 
fore, culminates  in  the  comparison  of  the  degrees  of  con- 
volutional complexity  to  be  met  with  among  the  different 
races  of  Man. 

In  taking  account  of  the  mere  size  of  the  Brain  in 
di.Terent  animals,  as  well  as  of  its  degree  of  convolutional 

la 


278  THE    BRAIN    OF    QUADRUPKDS    AND 

development,  in  reference  to  the  amount  of  Intelligence 
they  are  accustomed  to  display,  several  points  have  to 
be  borne  in  mind,  which  are  too  ai:>t  to  be  overlooked. 
Size  of  Brain,  and  with  it  convolutional  complexity,  must, 
for  instance,  be  closely  related  to  the  number  and  variety 
of  an  animal's  Sensorial  Impressions — the  raw  material  as 
it  were  of  Intelligence ;  but  it  must  be  also  largely  depen- 
dent upon  the  organism's  power  of  evoking  simple  Move- 
ments continuously  or  with  great  ene^'gy,  as  well  as  upon 
its  power  of  performing  very  varied  or  intricate  Movements, 
Herbert  Spencer  has  called  special  attention  to  this  latter 
point  of  view.* 

The  importance  of  taking  into  account  the  powers  of 
Movement  possessed  by  the  animal  is  fully  borne  out  by  the 
fact  that  the  Brain  attains  such  a  remarkable  size  in  the 
Shark,  as  well  as  in  the  Porpoise  and  the  Dolphin — all  of 
them  creatures  whose  Movements  are  exceptionally  rapid, 
continuous,  and  varied.  The  great  increase  in  the  size  of 
the  Cerebellum  in  each  of  these  creatures  is,  therefore,  not 
so  surprising;  but  it  seems  very  puzzling,  at  first  sight,  to 
understand  why  this  should  be  accompanied  by  a  co-ordinate 
increase  in  the  development  of  the  Cerebral  Hemispheres. 
For  this,  however,  there  are  two  causes,  the  one  general 
and  the  other  more  special.  It  is  a  fact  generally  observed, 
that  Sensorial  Activity,  and  therefore  Intelligent  Dis- 
crimination, increases  with  an  animal's  powers  of  Move- 
ment ;  and  secondly,  there  must  be  special  parts  of  the 
Cerebral  Hemispheres  devoted  to  the  mere  Sensory  Appre- 
ciation of  Movements  executed.  The  nerve  elements  lying 
at  the  basis  of  this  latter  appreciation,  however  they  may 
be  distributed  through  the  Hemispheres,  would  naturally 
be  the  more  developed  (and,  consequently,  all  the  more 
calculated  to  help  to  swell  the  size  of  the  Cerebrum),  in 
*  "  Principles  of  Psychology,"  vol.  i.  p.  192. 


CiiAP.  XVI.]  SOME    OTHER    MAMMALS.  279 

proportion  to  the  variety  and  continuance  of  the  Move- 
ments which  the  animal  is  accustomed  to  execute. 

Arrangement  of  Convolutions. — In  the  lowest  Quad- 
rupeds there  are  no  Convolutions  at  all.  This,  for 
instance,  is  the  case  with  Monotremes,  and  the  lower 
Marsupials  and  Kodents.  But  in  other  higher  forms 
Convolutions  exist,  and  are  arranged  in  accordance  with 
two  distinct  types  or  patterns,  which  have  heen  named 
respectively,  the  *  ohlique  '  and  the  '  longitudinal.'  The 
following  hrief  references  to  these  two  patterns  are  con- 
densed from  Owen's  account  of  them.^  It  is  not  intended 
to  give  anything  like  a  full  description  here,  hut  merely 
to  indicate  some  of  their  most  striking  peculiarities. 

The  '  ohhque  pattern  '  is  met  with  among  the  hoofed 
Quadrupeds,  viz.,  Kuminants,  Solipedes,  and  Pachyderms. 
The  '  longitudinal  pattern  '  pertains  to  other  Mammals, 
comprised  principally  within  the  orders  Carnivora  and 
Cetacea. 

A  third  or  *  transverse  pattern  '  is  common  to  the 
Quadrumana  and  Man,  as  will  he  shown  in  subsequent 
chapters,  and  on  this  we  shall  find  it  worth  while  to  bestow 
a  much  larger  amount  of  attention. 

Notwithstanding  the  very  numerous  diiferences  in  detail, 
certain  primary '  fissures  '  seem  to  be  common  to  the  three 
types.  One  of  the  most  constant  of  these  is  the  '  fissure 
of  Sylvius '  on  the  outer  surface  of  the  Hemispheres  ; 
while,  another,  also  very  constant,  is  the  *  fissure  of  the 
Hippocampus.'  The  latter,  situated  on  the  inner  aspect 
of  the  hemispheres,  has  already  been  alluded  to  as  cor- 
responding with  the  body  of  the  same  name  whicli 
projects,  in  each  hemisphere,  into  a  descending  pro- 
lont^ution  of  the  Lateral  Ventricle. 


'b' 


Aiuiloniy  of  the  Vertebrates,"  vol.  iii. 


280 


THE    BRAIN    OF    QUADRUPF.DS    AND 


The  ^Oblique  Pattern.' — The  simple  form  of  this  type  of 
coiiYolutional  arrangement  may  be  well  seen  in  the  small 

Fig.  89. 


Fig.  88. 


Fig.  88.— Brain  of  the  Rock  Coney  {Hyrax). 

Fig.  89. — Left  Cerebral  Hemisphere  of  the  Horse. 

Fig.  90. — Left  Cerebral  Hemisphere  of  the  Rhinoceros. 

Eock  Coney  (figs.  88,  93).     More   complete  forms  are  to 


Fig.  91. 


Fig.  92. 


Fio.  9L— Left  Cerebral  Hemisphere  Fig.  02.— Left  Cerebral  Hemisphere 

of  the  Stag  {Cervus).  of  the  Giraffe. 


be  seen  in  the  Horse  (fig.  89)  and  the  Rhinoceros  (fig.  90). 


Chap.  XVI.] 


SOME    OTHER    MAMMALS. 


281 


In  the  latter  the  hinder  parts  of  the  Hemispheres  are 
notably  expanded,  and  the  anterior  lobes  are  larger  in 
all  their  dimensions.  In  this  convolutional  plan,  as  the 
figures  borrowed  from  Owen's  '  Anatomy  of  the  Verte- 
brates '  show,  the  primary  convolutions  of  the  two  halves 
of  the  Cerebrum  converge  from  behind  forwards,  as  far 
as  the  anterior  third  of  the  Cerebral  Hemispheres — and 
thence  diverge  in  different  directions.* 


Fig.  Q3.— Brain  of  the  Rock  Coney, 

side  view. 


Fig.  94.— Brain  of  tlie  Giraffe, 
side  view. 


Starting  from  another  small  form,  the  Pigmy  Chevrotain 
(Tragulus),  we  may  find  a  similar  convolutional  develop- 
ment attaining  to  higher  t3^es  of  the  same  general  pattern 
in  the  Stag  (fig.  91),  the  Sheep,  the  Ox,  the  Giraffe 
(figs.  92,  94),  the  Camel,  the  Hippopotamus  and  the 
Elephant  (fig.  95).  The  greater  convolutional  complexity 
of  the  brain  in  these  larger  forms  is  represented  in  detail, 
as  Owen  has  pointed  out,  by  the  fuller  development  of  the 
'primary  fissures,'  by   their  more    sinuous  course,  and  by 

*  The  letters  and  numerals  in  the  several  figures  are  always  the 
same  for  corresponding  Convolutions  and  Fissures,  and  this  will 
materially  assist  the  reader  in  his  comparison  of  the  different 
forms.  The  explanations  of  these  references  are  given  by  Owen 
(loc.  cit.,  vol.  iii.  pp.  136,  137),  where  the  Fissures  and  Convolutions 
of  Mammalia  are  enumerated  mainly  in  their  order  of  constancy. 
Many  outline  figures  of  the  Cerebral  Convolutions  of  other  ani- 
mals will  likewise  be  found  in  this  work. 


282 


THE    BRAIN    OF    QUADRUPEDS    AND 


the  development  from  them  of  numerous  offshoots  in  the 
form  of  *  secondary  fissures.' 

The  *  Longitudinal  Pattern.^  This  mode  of  arrange- 
ment of  some  of  the  principal  convolutions  is  well  seen  in 
many  of  the  Carnivora  when  the  brain  is  looked  at  from 
above,  as  in  the  Cat  (fig.  96).  When  viewed  from  the 
side  the  surface  of  the  hemisphere  may  be  seen,  as 
Marshall  says,  to  be  divided  ''  into  four  principal  antero- 
posterior  convolutions,   which  seem    to   bend   in  simple 

curves  around  the  up- 
per end  of  the  Sylvian 
fissure,  one  above  the 
other,  and  pass  con- 
tinuously from  the 
anterior  or  frontal,  in- 
to the  middle  or  pa- 
rieto-temporal  lobe." 
This  is  well  shown  in 
figs.  98-100. 

In  the  larger  Feline 
animals  most  of  the 
primary  fissures  pre- 
sent short  secondary  branches.  In  the  Fox  and  in  the  Dog 
the  fissures  are  more  numerous  still.*  The  Cerebrum  is 
also  larger  and  narrower  anteriorly,  though  in  the  Bear  it 
is  again  found  to  be  more  oblong.  In  the  Seal  this  part  of 
the  Brain  attains  the  greatest  relative  size  and  complexity 
known  in  the  present  group. f  The  Hemispheres  are 
unusually  broad,  and  richly  convoluted  ;  but  a  comparison 
of  the  relative  depth  of  the   fissures  enables    the  primary 


Fio.  95.— Right  Cerebral  Hemisphere  of  the  Ele 
phant,  side  view,  much  reduced. 


*  This  is  move  obvious  in  the  Dog  tlian  in  the  Fox,  owing  to  the 
greater  number,  length,  and  depth  of  its  secondary  fissures. 

t  Excellent  figures  of  the  brain  of  the  Seal  are  given  by  Tiede- 
mann  in  his  '  Icones  Cerebri  ISimiarum.'     Tab.  2,  figs.  7,  8. 


Chap.  XVI.] 


SOME    OTHER    MAMMALS. 


283 


to  be  distinguished  from  those  of  the  secondary  order. 
The  mass  of  the  Hemispheres  behind  the  *  fissure  of 
Sylvius '  is  rehxtively  greater  than  in  other  Carnivora,  and  a 
larger  proportion  of  the  Cerebellum  is  also  covered  thereby. 
The  general  parallel  arrangement  of  the  convolution r 


Fig.  96.— Brain  of  the  Cat. 
(Tiedemanu.) 


Fig.  97  —Brain  of  the  Dog. 
(Tiedemann.) 


in  the  Carnivora  is,  as  Owen  points  out,  even  more  marked 
in  the  Cetacea,  This  may  be  seen  in  the  Porpoise 
(fig.  77),  and,  though  less  distinctly,  in  the  Dolphin 
(fig.  101).  The  breadth  of  the  Cerebral  Hemispheres  is 
most  striking  in  both  these  creatures— but  especially  in 


.—Brain  of  the  Coati.  Fig.  99.— Brain  of  the  Cat.   Fig.  100.— Brain  of  the  Fux. 


the  Dolphin.  The  convolutions  in  the  latter  ai-e  also 
exceedingly  complex,  so  that  in  this  respect  its  brain  stands 
at  present  at  the  head  of  the  well-known  representatives  of 
the  '  longitudinal  pattern,'  just  as  that  of  the  Elephant 


284 


THE    BRAIN    OF    QUADRUPEDS    AND 


(fig.   95)  does  at  the    bead  of  the  representatives  of  the 
'  obhque  pattern  '  met  with  among  Herbivora. 

It  is  somewhat  puzzHng  that  such  a  position  should  be 
taken  by  the  brain  of  a  creature  possessing  no  greater 
dimensions  than  the  Dolphin.  But  we  need  more  infor- 
mation as  to  the  exact  characters  of  the  brain  in  the 
larger  Cetacea,  in  which,  according  to  the  rule  previously 
specified,  the  complicacy  of  convolutions  ought  to  be 
extremely  well  marked — though  their  diminished  powers 


Fig.  101.— Brain  of  the  Dolijhin,  upper  aspect.     (Owen,  after  Tiedcmann.) 

and  diminished  customary  rate  of  Movement  would  afford 
a  set-off  in  the  contrary  direction.  While  one  of  the 
great  Whales  is  leisurely  moving  along  at  the  rate  of 
five  miles  an  hour,  a  Dolphin  may  and  often  does  easily 
cover  twenty  miles  in  the  same  time,  and  its  superiority  in 
regard  to  variety  of  Movements  would  probably  be  equally 
well  marked.* 

*  Since  this  Chapter  hns  been  in  the  printer's  hands,  a,  descrip- 
tion with  fi^nires  of  the  Brain  of  the  White  Whale  iJlhu/a)  has 
been  published  in  tlie  Journal  of  Anatomy  and  Pltiisioloiji/,  Jan. 
1879,  by  Dr.  Major. 


Chap.  XVr.]  SOME    OTHER    MAMMAI.S.  285 

According  to  Owen,  the  convolutions  of  the  laterrJ 
asj^ect  of  the  Hemispheres,  around  and  above  the  '  fissure 
of  Sylvius,'  are  more  undulating  or  interrupted — and 
therefore  less  neatly  defined — in  the  larger  Herbivora  than 
among  the  larger  Carnivora  and  Cetacea.  This  lack  of 
definition  is,  however,  carried  to  an  extreme  degree  in  the 
most  richly  convoluted  brains  of  both  types. 


CHAPTER  XVII. 

THE    BRAIN    OF    QUADRUMANA. 

The  Brains  of  Lemurs,  Monkeys,  Baboons  and  Apes, 
present  many  common  characters,  which  testify  to  the 
close  rehitionship  of  these  several  forms  with  one  another. 
A  sort  of  gradation,  though  not  that  of  a  single  series,  is  to 
be  met  with.  Beginning  in  the  Lemurs,  with  a  brain 
whose  structure  is  oiilj^  little  removed  from  that  of 
Bodents,  we  may  pass  by  means  of  most  distinct  transi- 
tion forms  to  the  more  highly  evolved  Cerebral  Hemi- 
spheres of  the  great  *  man-like  '  Apes — the  Chimpanzee, 
the  Gorilla,  and  the  Orang-utan. 

A  certain  community  of  structure  is  perceptible 
throughout  tlie  whole  series.  The  brain  of  every  Quad- 
rumanous  animal  is  distinguished  from  that  of  Quad- 
rupeds by  certain  wcll-deiined  characters.  Structures 
previously  existing  no  longer  manifest  themselves  ;  while, 
on  the  other  hand,  new  parts  become  diflerentiated  from 
the  old,  so  as  to  present  themselves  as  more  or  less  in- 
dependent structures. 

The  structures  existing  in  many  Quadrupeds,  but  not 
met  with  in  Quadrumana,  are  these  : — 

1.  Prolongations  from  Lateral  Yentricles  into  Olfactory  Lobes, 

2.  Listinct  '  pyriform  processes  '(or  '  hippocanipal  lobes')  on  the 

under  surface  of  the  Temporal  Lobes. 

3.  The  so-called  'trapezoid  bodies  '  of  the  Medulla  Oblongata.* 

*  Some  traces  of  these  structures  still  exist  in  the  Ilowler  Monkey. 


o  - 


Chap.  XVII]        THE    BRAIN    OF    QUADRUMANA.  287 

The  additional  characters  or  newly-differentiated  parts 
met  with  among  Quadrumana,  but  absent  in  lower  brutes, 
may  be  thus  enumerated  : — 

(1.)  The  differentiation  of  a  distinct  Posterior  (or 
'  Occipital ')  Lobe  in  each  of  the  Cerebral  Hemispheres, 
contaiuing  in  its  interior  a  '  posterior  horn  '  or  '  cornu  '  of 
the  Lateral  Ventricle,  which  is  marked  by  a  more  or  less 
distinct  projection  ('  Hip- 
pocampus Minor ')  corre- 
sponding with  a  fissure  on 
the  inner  surface  of  this 
lobe.*  The  development  of 
this  Posterior  Lobe  causes  ^_ 
the  Cerebral  Hemispheres  c  ^-\f'  ^^ 
to  extend  so  far  backwards  t  "^ 

as  to  cover  the  greater  part      ^'«-  102.-The  Brain  of  the  Brown  Macaque 
^  ^  (Macacus  nemestrinus),  side  view.    F,  Frontal 

or    the    whole    of   the    Cere-  L)be;  P,  Parletal  Lobe  ;  O,  Occipital  Lobe; 
111  C,  Cerebellum.    /,  /,  Greatly  prolonged  Fis- 

DeiiUm.  sy^g  yf  Sylvius. 

(2.)  The  appearance  of 
certain  '  primary  '  Cerebral  Fissures,  similarly  disposed  in 
all  Quadrumana,  and  the  gradual  development  of  other 
*  secondary  '  and  '  tertiary  '  Fissures — the  whole  series  of 
depressions  serving  to  divide  the  surfaces  of  the  Hemi- 
spheres into  Lobes  and  Convolutions  according  to  a  new 
but  constant  and  definite  pattern.  This  differs  notably  from 
the  two  principal  convolutional  patterns  of  Quadrupeds, 
though  it  agrees  in  all  essential  respects  with  what  we 
shall  find — though  in  a  more  developed  form — in  the 
Human  Brain. 

(3.)  The  existence  of  a   Central   Lobe,    corresponding 
with  the  part  known  in  Man  as  the  '  Island  of  Pteil.' 

(4.)  Another  additional  character  is  of  less  importance, 

*  The  Seal  is  the  only  Quadruped  in  which  a  '  posterior  cornu' 
is  known  to  exist,  as  a  prolongation  irom  each  Lateral  Ycnlricle. 


288  THE    BRAIN    OF    QUADRUMANA. 

and  does  not  pertain  to  tlie  bmin  in  all  Quadnimana ;  it 
exists  only  in  some  of  the  higher  Monkeys  and  Apes. 
It  consists  in  the  replacement  of  a  single  protuberance 
(the  '  mammary  ')  existing  at  the  base  of  the  brain  in 
Quadrupeds  by  two  smaller  projections  ('  Corpora  mamil- 
laria '  or  '  albicantia '),  side  by  side  in  the  same  situation, 
each  of  which  is  produced  by  a  bend  of  one  of  the  '  an- 
terior pillars  '  of  the  Fornix  (p.  273). 

(5.)  A  fifth  character  may  also  here  be  mentioned ; 
though  this  is  likewise  not  common  to  the  whole  class. 
Speaking  of  the  Olfactory  Lobes,  Prof.  Flower  says  :  * — • 
*'  In  the  large  majority  of  mammals,  the  base  of  these  lobes 
extends  backwards  to  the  under  surface  of  the  temporal 
lobe,  obliterating  the  lower  part  of  the  fissure  of  Sylvius, 
whereas  in  the  true  Apes  and  in  Man,  their  connexion 
with  the  Cerebral  Hemisphere  is  chiefly  with  the  anterior 
lobes  and  the  bottom  of  the  fissure  itself." 

The  convolutional  arrangement  we  have  now  to  con- 
sider is  known  as  the  'Transverse  Pattern/  No  dis- 
tinct transition  forms  are  known  between  it  and  either  of 
the  other  two  patterns,  though  Flower  f  seems  inclined 
to  think  that  this  may  hereafter  be  found  in  Bats  of  larger 
f5ize  than  have  hitherto  been  examined.  In  common 
Bats  the  Cerebrum  is  very  short  and  the  Sylvian  Fissure 
almost  non-existent.  Among  them,  in  fact,  no  species  exists 
of  sufficient  size  to  possess  sulci  on  its  surface.  But  this, 
as  Flower  remarks,  is  not  so  very  surprising  "  wdien  such 
markings  are  almost  absent  in  the  brain  of  a  true  Primate 
of  even  larger  size  (Hapale).**  For,  in  regard  to  convolu- 
tional development,  the  same  primary  rule  holds  good 
among  Quadrumana  as  with  Qaadi-ui)e(ls,  viz.,  that,  taking 

*  "  Traus.  of  Zoolog.  Soc.  18JG,"  vol.  v.  p.  108. 
Log.  cit.,  p.  109. 


Chap.  XVIL]       THE    BRATN    OF    QUADRUMANA. 


289 


representatives  of  the  same  genus  or  family,  small  forms 
commonly  have  comparatively  smooth  brains ;  while 
larger  animals  present,  in  proportion  to  their  size,  more 
and  more  richly  convoluted  Cerebral  Hemispheres. 

In  some  of  the  Lemurs  the  Cerebral  Hemispheres  are 
so  small  as  not  to  cover  more  than  one-half  of  the  Cere- 
bellum. There  is,  indeed,  a  kind  of  gap  between  the 
lower  and  the   lowest  Simians— that  is  between  the  old 


Fig.  104. 


Ftg.  105. 


Fig.  107. 


Fig. 


Fig.  103, 


Fig.  106. 


Fig.  103.— Brain  of  an  Aye-aye,  one  of  the  Lemurs. 

Fig.  104.— Brain  of  the  Marmoset  (Midas). 

Fig.  105.— Brain  of  the  Squirrel- Monkey  (Ca^^i^/irj'a:). 

Fig.  106. — Brain  of  a  Macaque. 

Fig.  107.— Brain  of  a  GibboTi. 

Fig.  108.— Brain  i.f  a  5th  n^aith  Human  Foetus.     (Owen.) 

and  new  world  Apes  and  Monkeys,  and  the  Lemurs. 
"  Every  Lemur  which  has  yet  been  examined,"  says  Prof. 
Huxley,'''  ''  has  its  cerebellum  partially  visible  from 
above,  and  its  posterior  lobe,  with  the  contained  posterior 
cornu  and  hippocampus  minor,  moie  or  less  rudimen- 
tary. Every  Marmoset,  American  monkey,  old  world 
monkey,  Baboon,  or  Man-like  ape,  on  the  contrary,  has 
its  cerebellum  entirely  hidden,  posteriorly,  by  the  cere- 
*  "Man's  Place  in  Nature,"  p.  96. 


200 


THE    BRAIN    OF    QUADRUMANA. 


bral   lobes,    and  possesses  a   large  posterior    cornu   with 
a  wcU-dovelopcd  hippocampus  minor." 

In    the  smallest  Lemurs,   the   Hemispheres  are  quite 
smooth,  or,  at  most,  show  traces  of  one  primary  fissure — the 

*  Sylvian'  (fig.  103,  5). 
Even  the  larger  Lemurs 
possess  only  a  few  pri- 
mary fissures. 

In  the  diminutive  hut 
active  Marmoset  (fig. 
101),  the  Cerebral  Hemi- 
spheres are  relatively 
argcr,  so  that  they  com- 
pletely cover  and  even 
slightly  overlap  the  pos- 
terior border  of  the  Cere- 
bellum. They  are,  how- 
ever, quite  smooth  and 
wholly  devoid  of  convolu- 
Only  one  fissure 
is  seen — the 'Sylvian' — 
forming  the  boundary  lino  Ix^twoen  pjirts  which  will  subse- 
quenlly  be  spoken  of  as  the  Parietal  and  the  Temporal 
Lobes.*  In  the  Squirrel  Monkey,  another  small  allied 
form  also  notable  for  its  extremely  active  habits,  a  fissure; 
below  and  behind  the  Sylvian  is  added — known  as  the 
*  ])arM,nel  fissure  '  (fig.  105,  9).  This  runs  along  the  centre 
of  tlio  TcMuporal  Lobe,  and  backwards  towards  the  upper 
and  inner  edge  of  the  Hemisphere.  Both  these  fissures 
are  less  vertical  and  slope  backwjirds  more  than  the  corre- 

*  Tlic  names  of  these  lobes  of  ilio  Brain  nre  derived  from  those 
of  the  bones  of  the  skull  ac^ainst  which  they  lie.  'I'he  two  lobes 
above  named  together  constilnto  what  was  formerly  prineipally 
ripokeii  of  as  the  '  Midillo  Loue.' 


Fin.  100.  — Hv.iin  (it  tiio  iidwlor  Monkey  (/I/// 
cetcs),  Hccn  from  iibovo.    (Duiicjui.)   Ij,  Lungitu-  tlOUS 
diual  Fis.suro  ;  F,  Fissuro  of  Sylvius. 


CiiAP.  XVII.]        THE    BRAIN    OK    QIJADHUMANA. 


291 


sj)oii(liiio;  fissures  in  any  Lomur  (lio-.  10:3)  in  which  ih(>y 
arc  present. 

The  Howler,  like  the  Marmoset  and  the  Squirrel 
Monkey,  is  a  New  World  form.  The  former,  in  fact, 
is  the  larn-cst  of  the 
series,  and  is  usually 
supposed  to  helong 
to  the  highest  group 
of  these  American 
Monkeys.  lis  l)rain, 
however,  is  very 
poorly  developed  (lig, 
]()!)),  and,  consider- 
ing its  size,  possesses 
very  few  surface 
markings.  It  is  re- 
markahle  chiefly  for 
the  very  small  size  of 

the  Occipital,  and  the  Fm.  no.— nram  of  the  Manpabcy  (CercopWiecus 

P    i-i      1         1                   ,         n  aihiopH},  ui)pGr  iiHjicct.  (Vogt. )  F,  Kroiital ;  P,  P^ric- 

lUU     development     OI  tal;  and  O.  occipital  Lobes.     L,  Orcat  Longitudinal 

the   Temi)()ral  Lobes.  ''i««"'*o;  H,  Kinsurcof  Uolando;  V,  K.xtcmall'onK'n- 

...  <Hcular  Fisstn-o  ;  K,  Operculum.     A,    A,    Aseending 

In      connection     with  Frontal  ;»•,  «'^  »:>,  Fir.-t,  Second,  and  Thin]   Tiers  of 

the   VerV  Sni'lll     Oeci-  '''"i'^'^^  <^""^*'J"tion.s.   I},  n,  Ascending  Parietal;  li\ 

,   '  ''-.  I''irst  and  Second  Tiers  of  Parietal  Ct)nvolulion«. 

pital  Lobes,  Flower*  «K  <I',  First  and  second  Tiers  of  Occipital  Cunvoln- 

haS  noted  an  almost  ''"I'lilssinn-le  no,nc,u.lature  f,,r  the  ('onv..luii..nsis 
complete  abs(niCe  of  ^'^^t  of  n.  Wagner,  excelling  that  A,  an<l  H,  are 
.,        I^  ,  ^  _  nanii'd  by  Idiii  Anterior  and   Posterior  Cent  i-al  <  on- 

tlie   J^jXternai  aJld  Jn-    v,.liiti„iis.     'Ihougli  it  is  a  terniijiology  which  is  })y 

ii'ans  \vitiio\it  merit,  it  has  not  been  commonly 


adopted.) 


ternal  Perpendicular 

Fissures.    'J'he  brain 

of  the  Howler  Monkey  is  also  remarkal)le  for  the  extreme 

backward  extension  of  the  Sylvian  Fissun^s  [v,  v),  each  of 

which  almost  reacli(>s  the  upper  and  inner  border  of  its 

corresponding  hemisphere. 

*  'Ti-occcd.  of  /ioulog.  Soc."  18(5  !•,  p.  '.VA!^),  V\.  xxix. 


292 


THE   BRAIN    OF    QUADRUMANA. 


In  the  Capuchins,  among  the  new  world  Monkeys,  as  well 
as  in  the  old  world  '  Dog-like '  forms,  viz.,  the  Baboons, 
Macaques,  and  Monkeys  proper,  together  with  the  Gib- 
bons (which  are  usually  regarded  as  the  lowest  of  the  '  Man- 
like' Apes),  the  Fissures  and  Convolutions  become  more 
numerous,  whilst  the  Cerebral  Hemispheres  are  larger,  so 
that  they  now  uniformly  cover  the  whole  of  the  Cerebellum. 
A  good  notion  of  the  mode  of  distribution  of  the  Fissures 
on  the  outer  surface  of  the  Hemispheres  may  be  gathered 
from  the  outline  diagrammatic  sketches  of  these  parts  in 

the    Macaque    and 
^        ^  JC  tl^e    Gibbon    (figs. 

^     '  106,  107) ;  especi- 

ally if  they  are  com- 
pared with  corre- 
sponding sketches 
of  the  much  sim- 
pler brains  of  the 
Marmoset  and  the 
Squirrel  Monkey 
(figs.  104,  105). 

In  the   brain  of 
J.' 

the      Mangabey 

Fig.  Ill,— Brain  of  Mangabey,  side  view.  (Vogt.)  Some    .„  -[^C^        1  1  1  { 

of  the  refere . . ces  are  the  same  as  for  fig.  HO.  8,  tiylvian  (Hg S .  i i U ,  1 1 1  j , 
Fissure.  T,  Temporal  I  obc.  t',  c2,  c3,  First,  Second,  and  r^-j^^]^  also  in  that 
Third  Tier.s  of  Touipural  L'onvjhitions. 

of  the  Wanderoo 
(figs.  112,  I  IB),  which  is  very  similar,  the  principal  primary 
fissures  of  the  Cerebral  Hemispheres,  and  therefore  the 
included  portions  or  Lobes,  are  quite  distinct.  Thus  R, 
]  epresents  the  '  fissure  of  Rolando  '  which  separates  the 
Frontal  from  thcPjirietal  Lobe;  s,  is  the  *  fissure  of  Sylvius,' 
constituting  the  upper  boundary  of  the  Temporal  Lobe, 
and  separating  it  from  the  Parietal'  ;  v,  is  the  vertical  or 
*  perpendicular  fissure  '  which  is  obvious  on  the  inner  as 


Chap.  XVII. ]        THE    BRAIN    OF    QUADRUMANA. 


293 


well  as  the  outer  surface  of  the  hemisphere,  and  serves 

to  mark    off  the  Occipital  Lobe.     Another   well-marked 

sulcus,    known   as 

the    'parallel    lis-  ^ 

sure/    runs   along 

the  outer  face  of  the 

Temporal  Lobe. 

Kudimentary 
Convolutions  show 
themselves  on  the 
Frontal  Lobe, 
which  is  bounded 
posteriorly  by  a 
well-marked  'as- 
cending convolu- 
tion' (a,  a).  An- 
other convolution, 
equally  distinct  (b, 
b),  forms  the  an- 
terior boundary  of  the  Parietal  Lobe 
though  large,  is 
still  almost  free 
from  any  trace  of 
convolutions,  and  F 
its  anterior  border 
(k)  is  quite  distinct. 
This  anterior  bor- 
der— or  '  Opercu- 
lum,' as  it  has  been 
termed — has  been 
cut   away    in     fig.  jr 

113,     so  as  to   show      Fto.  113.— Brain  of  the  Wanderoo,  side  view. 
a  small  convolution  References  as  in  fig.  111. 

marked  (x),  known  as  one  of  the  'bridging  convolutionSo' 


Fig.  112.— Brain  of  the  Wanderoo  {JSIacacm  silenus), 
upper  aspect.     (Vogt.)    References  as  in  fig.  110. 


The  Occipital  Lobe, 


(Vogt.) 


294 


THE    BRAIN    OF    QUADRUMANA. 


These  latter  folds  become  farther  developed  in  the  Orang, 
and  still  more  so  in  Man. 

In  the  Baboon,  the  Convolutions,  as  may  be  seen  from 
fig.  114,  are  pretty  distinctly  defined  on  the  Frontal  and 
Parietal  Lobes,  and  they  are  also  more  distinct  on  the 
Occipital  than  they  have  been  in  either  of  the  forms 
previously  mentioned.  The  Frontal  Lobes,  too,  are  fuller 
and  less  pointed  than  they  are  in  lower  terms  of  the  series. 


We  may  now  pass  to  a  brief  consideration  of  the  Brain 

in  the  highest  representa- 
tives of  the  Quadrumana  at 
present  existing,  viz.,  the 
three  great  *  man-like ' 
Apes — the  Chimpanzee,  the 
Gorilla,  and  the  Orang. 

No  differences  in  the 
brain  characters  of  these 
animals  have  been  found 
sufficiently  marked  in 
amount  or  in  nature  to 
enable  us  to  say  that  one 
of  them  is  very  unmistak- 
ably hic^her  than  the  others. 

Fig.   114.-  Braiu   of  the  Baboon  (Ci/noce-  "  t      •  •    t      i 

phalus  pupio),  upper  aspect.     (Vrolik,  after  SomO      distinguished      aiia- 

^rt>  ^7P;"'^^^j:I^f;"^**;;*^^^"^^^tomis^  disposed    to 

of  a  Hiiman  Foetus  of  b-i  th  month,  in  regard  i^ 

to  its  convolutional  development.  F,  Frontal  tllillk    that    tllO    braill    (liav- 

Lobe ;  O,  Occipital  Lobe.  .  i    ,       ■  i  j     j    i 

mg  regard  to  the  sum  total 
of  its  characters)  of  the  Chimpanzee  is  the  simplest,  and 
that  of  the  Orang  the  most  highly  developed.  Others,  how- 
ever, give  the  first  place  to  that  of  the  Gorilla. 

The  brain  of  a  Chimpanzee  was  carefully  described  and 
figured  in  1861  by  Prof.  Marshall."*     The  animal  was  not 
^  "Nat.  Hist.  Review,"  vol.  i.  p.  296. 


CiiAP.  XYIL]        THE    BRAIN    OP    QUA  DRUM  AN  A.  295' 

an  adult.  It  was  both  young  and  small;  its  height  being 
2  ft.  4  in.,  its  weight  16J  lbs.,  whilst  the  weight  of  its 
brain  was  14  ozs.  The  proportion  of  its  brain-weight  to 
its  bod}^- weight  was  therefore  1:19. 

The  brain  of  an  Orang  also  has  been  described  with 
great  care  and  minuteness  by  Prof.  Kolleston.*  It  was 
taken  from  a  young  male,  weighing  IGJlbs.,  whose  height 
was  2  ft.  7  in.  As  the  weight  of  the  brain  was  12  oz., 
its  weight  compared  with  that  of  the  body  was  1  :  22* 3. 

Our  knowledge  of  the  brain  of  the  Gorilla  is  still  very  im- 
perfect ;  as  of  the  three  specimens  which  have,  as  yet,  been 
examined,  one  was  in  a  very  poor  condition,!  and  the  two 
others  were  taken  from  very  dissimilar  animals — the  one, 
examined  by  Broca,  being  an  adult  male,!  and  the  other  a 
young  specimen,  only  six  months  old.§  Broca  suspects, 
moreover,  that  there  may  be  two  species  of  Gorilla,  instead 
of  one  as  hitherto  supposed  ;  and,  while  admitting  that 
the  brain  of  the  Orang  presents  a  slightly  higher  type  than 
that  of  the  other  two,  he  considers  the  brain  of  the  Gorilla 
to  be  on  the  whole  simpler  than  that  of  the  Chimpanzee. 

The  Cerebral  Hemispheres  in  the  Chimpanzee  were 
much  smaller  in  proportion  to  the  size  of  the  Cerebellum 
than  they  are  in  the  human  Brain.  They,  however, 
slightly  overlapped  the  Cerebellum,  and  this  organ  was 
flatter  and  wider  than  it  is  in  Man. 

Looked  at  from  above  (fig.  115)  the  Chimpanzee's 
brain  has  a  short,  wide,  ovoid  form,  though  in  the  lower 
races  of  Man  it  has  a  long,  ovoid  outline.     Seen  in  profile, 

*  "  I^at.  History  Eeview,"  1861,  p.  201. 

t  That  of  an  adult  female,  examined  by  Gratiolet,  in  1860. 

J  "Etude  sur  le  Cerveau  du  Gorille,"  Revue  d' Anthropologie^ 
1878. 

§  This  was  examined  by  Drs.  Bolau  and  Pansch,  and  their 
account  was  made  the  subject  of  some  interesting  comments  by 
Prof.  G.  D.  Thane  ("  Nature,"  December  14,  1876). 


296 


THE    BRAIN    OF    QUADRUMANA. 


the  Frontal  Lobes  are  short  and  shallow,  though  as  a  whole 
its  upper  outline  is  decidedly  convex.  The  lower  and 
hinder  boundary  of  the  Cerebral  Hemisphere,  Avhen  com- 
pared with  the  correspondinfij  region  in  Man,  is  notable  for 
its  concavity  and  slanting  direction  from  behind  forwards. 
This  is  due  to  the  marked  shallowness  of  the  Occipital 


Fig.  115.— Brain  of  the  Chimpanzee,  nrpor  aspect,  with  upper  part  of  Rij^ht 
Hemisphere  cut  away  so  as  to  expose  Lateral  Ventricle.  (Vogt,  after  Marshall.) 
Letters  of  reference  for  Left  Hemisphere  similar  to  those  of  fig.  110.  c  s,  Oorp\is 
Striatum,  id  the  anterior  conm  of  the  Ventricle  ;  c  a.  Hippocampus  Major,  in  the 

desceiiding  conm  ;  //  ;/(,  Hippocanipiis  Minor,  in  the  i)o.stcrior  cornu. 

Lobes  in  the  Chimpanzee — these  divisions  of  the  Brain 
being  wide  but  not  deep.  The  same  peculiarity  is  to  b^ 
seen  in  the  brain  of  the  Orang  (fig.  121). 

The  Frontal  Lobes  in  the  Orang  have  a  recurved  beak- 
like termination  (seen  also  in  fig.  121) ;  and  if  we  turn  the 


Chap.  XVII.]        THE    BRAIN    OF    QUADRUMANA. 


297 


organ  over  so  as  to  examine  its  base,  the  orbital  or  under 
surface  of  these  lobes  is  found  to  be  distinctly  concave,  as  it 
is  in  most  of  the  larger  Monkeys  and  Apes.  Just  behind 
these  parts,  the  lower  terminations  of  the  two  Temporal 


c.^. 


ecu 


Am. 


Fig.  116.— Brain  of  a  Human  Idiot.  (Vogt,  after  Theilc.)  This  brain,  examined 
by  Theile,  weighed  only  lO'O  oz.  (300  grammes).  With  the  exception  of  one,  it  is  the 
smallest  Male  Idiot's  Brain  whose  character.';  have  been  recorded. 

This  figure  is  placed  here  for  comparison  with  that  of  the  brain  of  the  Chimpanzee  ; 
the  letters  of  reference  being  the  same  in  each  of  them. 

Lobes  approach  rather  close  to  one  another  (fig.  118),  and 
between  them  are  two  *  Corpora  albicantia,'  as  in  Man. 

The  Sylvian  Fissure  in  the  Cbiinpanzee  as  well  as  in 
the  Gorilla  (fig.  117),  and  the  Orang  (tig.  li^l),  is  much 
less  horizontal  than  it  is  in  Man.     In  this  respect  it  pretty 


298 


THE    BRAIN    OF    QUADRUMANA. 


closely  resembles  the  disposition  met  with  in  the  brain  of 
the  Mangabey,  the  Wancleroo,  and  other  of  the  *  Dog- 
like' Apes  (figs.  Ill,  113).  Its  direction  more  nearly 
approaches  the  horizontal  in  the  Gorilla  than  in  the  other 
two. 

The  Fissure  of  Rolando  is  very  distinct  in  the  Chim- 
panzee, though  its  upper  extremity  is  situated  in  front  of 
the  middle  of  the  brain,  instead  of  being  more  decidedly 


j:s  w 

Fig.  117.— Brain  of  tlic  Gorilla,  side  view.  (Afror  Bola-i  and  Pansch.)  I,  Frontal 
lobe;  II,  Fissure  of  Rolando;  111,  Parietal  lobe  ;  IV,  Temporal  lobe.  0.  Cerebellum  ; 
fs,  Ussure  of  Sylvius;  s  c,  External  Periiendicular  Fissui'e  separating  Parietal  from 
Occipital  Lobe. 


behind  it  as  in  Man.  According  to  Marshall,  a  little  more 
than  one-third  of  the  surface  of  the  Cerebrum  lies  in 
front  of  the  Fissures  of  Sylvius  in  the  Cbimpanzee,  instead 
of  nearly  one-half  as  in  Man.  In  the  Orang  the  propor- 
tionate size  of  the  Frontal  Lobes  is  strictly  intermediate. 
In  the  Orang,  too,  the  Fissure  of  Eolando  (fig.  121)  is 
very  strongly  bout  upon  itself — almost  at  right  angles — so 
that  its  lower  extremity,  instead  of  being  in  advance  of  the 


Chap.  XVII.]        THE    BRAIN    OF    QUADRUMAxXA.  299 

anterior  extremity  of  the  Temporal  Lobe,  as  it  is  in  the 
Gorilla  (fig.  117),  is  more  nearl}^  opj^osite  the  middle  of 
the  Sylvian  Fissure.  This  peculiar  disposition  of  the 
fissure  of  Rolando  in  the  Orang  coincides  with  a  greater 
comparative  development  of  the  lower  (or  third)  tier  of 
*  frontal  convolutions,'  and  with  a  notable  falling  off  in  the 
size  of  the  lower  half  of  the  '  ascending  parietal '  con- 
volution. On  the  other  hand,  the  disposition  met  with 
in  the  Gorilla  seems  to 
be  due  principally  to  the 
greater  development  in 
it  of  the  lower  part  of 
the  parietal  region  of  the 
Hemispheres.  Thus,  the 
great  size  of  the  '  supra- 
marginal  lobule '  and  of 
the  lower  part  of  the  '  as- 
cending parietal'  convo- 
lution, seems  to  cause 
the  lower  half  of  the 
fissure  of  Rolando  to  be 
pushed  decidedly  for- 
wards. These  peculiari- 
ties    do     not     appear     to      Fig    IIS.— Brain  of  Crang,  view   of  base    or 

bflVP       hpPT)        nvPvinncilv  ""'^^'"  '''^P^'^^-    C'^^en,  after  Tiedemann.)   to.i.- 
nave        Deen        pi  e^  lOU  Sn   ^^,^^,^  ^.^^^  ^^^^  ^^  Human  Brain  Fig.  144. 

noticed  by  anatomists. 

The  External  Perpendicular  Fissure  is  particularly 
well  marked  in  the  Chimpanzee  (fig.  115),  though  it  is 
seldom  distinctly  visible  in  the  human  brain.  In  the 
Chimpanzee  it  is  not  crossed  by  any  superficial  '  bridging 
convolutions,'  so  that  its  posterior  border  (or  'Operculum  ' 
as  it  is  called  in  lower  forms  of  Quadrumana)  is  uninter- 
rupted. This  fissure  is  continued  on  the  inner  side  of  the 
brain  as  the  'Internal  Perpendicular  Fissure'  (fig.  120, /p). 


300 


THE    BRAIN    OF    QUADRUMANA. 


*  bridging 
'      which 


In  the  Gorilla  also,  the  External  Perpendicular  Fissure 
(fig.  117,  s  c)  is  very  distinct  and  long,  its  hinder  margin 
(Operculum)  being  convex  anteriorly,  and  somewhat  more 
sinuous  than  it  is  in  the  Chimpanzee.  The  first  '  bridging 
convolution '  emerges  from  beneath  it  above.  But  in  the 
Orang  this  Perpendicular  Fissure  is  sometimes  much 
shorter  and  less  obvious  (fig.  119)  than  it  is  in  either  of 
the  other  two  great  Apes,  so  that  in  this  respect  its  brain 
approaches  more  closely  to  that  of  Man.     It  is  sometimes 

interrupted  above  by 
an  upper 
convolution 
has  a  superficial  posi- 
tion of  this  kind  in 
no  other  of  the  Quad- 
rtimana,  excei:)t  in 
Ateles. 

According  to  Ptolle- 
ston  this  superficial 
position  of  the  upper 
or  first '  bridging  con- 
volution '  is  not  con- 
stant in  the  Orang  or 

Fig.  119.— Brain  of  Orang,  upper  aspect.  (Duncan,  eVCU    in     Man while 

in  both  it  may  at 
times  be  present  on 
one  side  and  absent  on  the  other.  He  adds  : — "  In  the 
higher  species  of  the  order  Apes,  as  in  the  higher  varieties 
of  the  species  Man,  we  find  variability  the  rule,  uniformity 
the  exception ;  in  the  lower  species,  as  in  the  lower  varie- 
ties of  Man,  the  reverse  condition  obtains." 

The  second  '  bridging  convolution '  which  is  always 
present,  superficial  and  easily  recognizable  in  Man,  is  said 
to  be  as  invariably  absent  in  the  Chimpanzee  and  the 


from  specimen  in  Museum  of  Royal  College  of  Sur- 
geons.)    F,  Frontal  Lobe  ;  O,  Occipital  Lol)e. 


Chap.  XVIL]       THE    BRAIN    OF    QUADRUMANA. 


301 


Orang,  and  it  was  also  absent  in  the  young  Hamburg 
Gorilla. 

The  three  principal  Fissures  already  referred  to,  viz., 
the  Sylvian,  that  of  Kolando,  and  the  External  Perpen- 
dicular, divide  the  outer  surface  of  the  Hemisphere  into 
four  Lobes,  in  the  manner  already  described  (p.  292)  ; 
and  though  their  relative  size  is  very  different  in  the  several 
creatures  in  which  they  exist,  these  Lobes  may  be  considered 


Pro.  120. — Brain  of  Gorilla,  1  ugitudinal  section,  inner  usijuct.  (Bolauand  Panseh.) 
8.  cm,  Calloso- marginal  I'issure  ;  ./.  p,  Internal  Perpendicular  Fissure  ;  /.  c,  Calcarine 
Fissure,  being  the  posterior  part  of  the  '  Fissure  of  the  Hippocampus. ' 

to  represent  strictly  homologous  parts  in  inferior  Monkeys, 
in  higher  Apes,  and  also  in  the  Brain  of  Man. 

Concealed  by  the  lips  of  the  Sylvian  fissure,  and  form- 
ing part  of  its  floor,  we  may  find  the  small  Central  Lobe, 
commonly  known  as  the  'Island  of  Eeil.'  This  part  be- 
comes well  marked  and  even  complex  in  Man,  and,  accord- 
ing to  Flower,*  is  traceable,  except  in  the  diminutive 
Marmoset,  throughout  the  Quadrumanous  series,  though 
it  is  absent  in  all  other  Mammalia. 

*  "  Trans,  of  Zoolog.  Soc,  1860,"  vol.  v.  p.  108. 
14 


802  THE    BRAIN    OF    QUADRUMANA. 

Three  other  Fissures  of  secondary  importance  are  easily 
recognizable  in  each  of  the  great  man-like  Apes,  as  well 
as  in  many  of  the  lower  forms,  viz.,  the  Parallel  Fissure , 
situated  parallel  with,  and  posterior  to,  the  fissure  of  Syl- 
vius, in  the  long  axis  of  the  Temporal  Lobe ;  the  Calloso- 
marg'inal  Fissure  on  the  inner  side  of  the  Hemisphere 
(fig.  120),  just  above  the  Corpus  Callosum  ;  and  the  Fissure 
of  the  Hip2^ocampus,  situated  near  the  junction  of  the  inner 


Fig.  121.— Brain  of  Orang,  side  view.    (Vogt,  after  Gratiolet.)  Letters  of  reference 
as  in  Figs.  Ill,  133,  and  142— with  which  compare. 

with  the  under  surface  of  the  posterior  half  of  the  Hemi- 
sphere (fig.  120,/.  c). 

Next  to  the  Sylvian,  the  '  Parallel  Fissure'  is  the  most 
constant  of  the  markings  on  the  outer  surface  of  the  Cere- 
bral Hemisphere  (fig.  105)  ;  though  after  this,  according  to 
Flower,  "  the  most  persistent  fissure  on  the  outer  face 
appears  to  be  the  one  bounding  the  upper  border  of  the 
angular  gyrus  "  (fig.  107,  ')n).  The  same  anatomist  adds  : — 
*'  But  it  is,  perhapSj  the  sulci  of  the  inner  face  of  the  hemi- 


Chap.  XVII.]        THE    BRAIN    OF    QUADRUMANA.  303 

sphere  that  are  most  characteristic  of  the  Primates,  and 
offer  the  most  striking  difl'erential  features  from  other 
Mammalia."  The  posterior  part  of  the  '  Hippocampal 
Fissure,'  named  '  Calcarine  '  by  Huxley  (lig.  120,  /.  c), 
is  peculiar  to  Man  and  the  Quadrumana.  It  sometimes 
persists  deeply  marked  in  the  lowest  forms,  when  every 
other  trace  of  a  fissure  except  the  Sylvian  has  disappeared. 
The  Sylvian,  however,  is  found  in  lower  Mammals,  and 
the  *  Calloso-Marginal,'  which  is  usually  very  distinct 
among  Quadrumana  (fig.  120,  s.  cm),  seems  also  to  exist 
in  the  great  majority  of  Mammals. 

The  part  of  the  outer  face  of  the  Hemisphere  known  in 
Man  as  the  '  Supra-Marginal  Lobule'  (figs.  133,  142,  h^  JJ"), 
existing  above  the  posterior  end  of  the  fissure  of  Sylvius, 
was  said  by  Gratiolet  to  be  invariably  absent,  in  the  great 
*  man-like'  Apes.  But,  according  to  Prof.  Eolleston,*  "  the 
development  of  this  part  is  very  frequently  asymmetrical 
on  the  two  sides  of  the  same  brain,  and  its  development 
in  any  two  human  brains,  taken  at  hap-hazard,  is  pretty 
sure  to  present  the  greatest  differences."  It  would  seem, 
moreover,  that  a  simple  representative  of  this  structure  is 
unquestionably  to  be  found  in  the  Chimpanzee,  that  it  is 
better  developed  in  the  Orang  (fig.  121,  ^Vand  posterior 
thereto),  and  that  it  is  larger  still  in  the  Gorilla  (fig.  J 17): 
so  that  the  supposition  as  to  its  absence  in  these  creatures 
was  a  mistake,  and  we  certainly  have  not  in  this  direction, 
as  Gratiolet  thought,  a  differentiating  mark  between  the 
brain  of  the  great  Apes  and  that  of  Man. 

The  several  Convolutions  will  not  now  be  further  referred 
to,  but  the  names  of  many  of  them  may  be  ascertained 
by  a  careful  study  of  figs.  115-121.  Although  the 
letters  and  numbers  affixed  to  corresponding  parts  in  these 
Bcveral  representations   of  the  brain  of  the  Chimpanzee, 

*  Loc.  cit.,  p.  212. 


804  THE    BRAIN    OF    QUADRUMANA. 

the  Gorilla,  and  the  Orang,  are  not  in  all  cases  the  same, 
the  reader  will  have  little  difficulty  in  recognizing  in  each 
the  parts  which  correspond. 

No  great  difference  exists  between  these  three  Apes  in 
regard  to  the  Internal  Topography  of  their  brains,  so  far 
as  it  is  known.  The  following  particulars  refer  in  the 
main  to  that  of  the  Chimpanzee  (fig.  115). 

The  Corpus  Callosum  is  shorter  and  thinner  than  in 
Man,  and  Prof.  Marshall  concludes  that,  in  proportion  to 
the  size  of  the  brain,  its  bulk  is  twice  as  great  in  Man  as 
it  is  in  the  Chimpanzee.  The  Anterior  Commissure  is 
proportionally  large,  and  so  is  the  soft  or  Middle  Com- 
missure. The  Posterior  Commissure,  however,  is  small. 
The  Fornix  is  thin,  and  the  '  tenia  semicircularis '  is 
just  discernible  as  a  thin  white  band  lying  over  the 
line  of  junction  between  the  Thalamus  and  the  Corpus 
Striatum,  and  joining  the  pillars  of  the  Fornix  an- 
teriorly. 

The  Lateral  Yentricles  are  rather  large,  and  its  three 
Cornua  are  quite  distinct.  The  central  part,  known  as 
the  body  of  the  ventricle,  corresponds  with  the  parietal 
lobe  externally ;  its  anterior  cornu  is  prolonged  into 
the  frontal  lobe ;  its  descending  cornu  traverses  the  tem- 
poral lobe,  and  its  posterior  cornu  extends  into  the  occi- 
pital lobe.  On  the  inner  side  of  the  descending  cornu  is 
the  projection  (fig.  115,  c  a),  known  as  the  '  Hippocampus 
major,'  from  which  the  posterior  pillar  of  the  fornix  is 
derived.  On  the  inner  side  of  the  floor  of  the  posterior 
cornu  is  the  'Hippocampus  minor'  or  'calcar  avis,'  a  small 
eminence  {h  m),  produced  by  a  deepening  of  part  of  the 
fissure  of  the  hippocampus  (the  '  calcarine '),  to  which  it 
corresponds  externally.  Between  this  projection  and  the 
upper  part  of  the   bend   of  the  larger  Hippocampus   is 


Chap.  XVII]       THE    BRAIN    OP"    QUADRUMANA.  805 

another  small  projection  ('  eminentia    collatcralis  '),  which 
is  also  recognizable  in  Man. 

Of  the  Corpora  Quadrigemina  the  anterior  pair  are  the 
larger,  though  they  are  somewhat  less  prominent  than  the 
other  couple.     The  Pineal  Body  is  rather  large  and  soft. 

In  its  general  shape  the  inferiority  of  the  brain  of  the 
Chimpanzee,  as  compared  with  that  of  Man,  is  most 
marked  in  the  direction  of  vertical  height ;  in  the  rela- 
tively small  dimensions  of  its  frontal  lobes ;  and  in  the 
similarly  small  relative  bulk  of  its  occipital  lobes. 

The  outline  of  the  brain  of  the  Gorilla,  as  seen  from 
above,  is  that  of  a  broad  ovoid,  though  it  is  not  so  broad 
as  that  of  the  Chimpanzee,  Its  anterior  lobes  are  wide, 
rather  shallow,  bat  long,  more  so  even  than  in  the  Orang — 
though  the  latter  exhibits  a  greater  complexity  of  its  con- 
volutions. In  vertical  height,  too,  its  Hemispheres  seem  de- 
cidedly superior  to  those  of  the  Chimpanzee  and  the  Orang; 
but  its  posterior  or  occipital  lobes  are  distinctly  smaller  and 
shorter  than  they  are  in  either  of  the  other  two  '  man -like ' 
Apes.  The  parietal  lobes  of  the  Gorilla  are  notable  for 
their  great  size  both  in  width  and  depth,  while  the  con- 
volutions of  this  region  are  well  defined,  and  decidedly 
more  developed  than  in  other  parts  of  the  brain.  Its 
*  supra-marginal  lobule '  especially,  is  larger  and  better 
defined  than  it  is  in  either  of  the  other  'man-like'  Apes. 
The  temporal  lobes  are  comparatively  smaller,  while  their 
convolutions  are  simple,  though  not  very  symmetrical  on 
the  two  sides. 

Owing  to  the  greater  narrowness  of  its  anterior  lobes, 
the  outline  of  the  brain  of  the  Orang,  as  seen  from  above, 
is  not  nearly  so  rounded  as  it  is  in  the  Chimpanzee,  and 
it  is  also  rather  narrower  than  that  of  the  Gorilla.  The 
anterior  lobes  are  somewhat  deficient  in  length  and  depth, 


806  THE    BRAIN    OF    QUADRUMANA. 

and  in  consequence  of  this,  as  well  as  of  the  smaller 
relative  development  of  tlie  parietal  lobes,  the  Sylvian 
fissure  deviates  much  more  from  the  horizonal  position 
in  the  Orang  than  in  either  the  Gorilla  or  the  Chim- 
panzee.* The  lower  and  posterior  border  of  the  Cerebral 
Hemispheres  is  notably  more  oblique  than  it  is  in  Man, 
owing  principally  to  the  small  size  and  shallowness  of  the 
occipital  lobes.  In  this  latter  respect,  as  well  as  in  the 
generally  deficient  depth  of  the  Hemispheres  as  compared 
with  those  of  Man,  the  Chimpanzee  and  the  Orang  are 
closely  allied. 

On  the  whole,  it  would  appear  that  the  convolutions  of 
the  Gorilla's  brain  are  slightly  more  subdivided  and  com- 
plex than  those  of  the  Chimpanzee  ;  though  in  this  respect 
the  brain  of  the  Orang  is,  to  about  the  same  extent, 
superior  to  that  of  the  Gorilla.  As  regards  the  want  of 
exact  symmetry  of  many  of  the  corresponding  convolutions 
of  the  two  Cerebral  Hemispheres,  that  of  the  Orang  also 
approaches  most  closely  to  the  still  more  marked  asym- 
metrical condition  of  the  brain  of  Man. 

*  This  direction  is  very  well  seen  in  the  figure  given  by  Prof. 
Bolleston  (loc.  cit.,  pi.  3,  fig.  1),  though  it  is  not  so  distinct  in  that 
of  Gratiolet  (see  fig.  121  in  text). 


CHAPTER  XVin. 

THE    MENTAL    CAPACITIES    AND    POWERS   OF   HIGHER  BRUTES. 

In  a  previous  chapter  some  account  has  been  given  of 
the  instinctive  and  occasional  actions  of  the  higher  Social 
Insects,  with  the  effect  of  disclosing  the  extremely  routine 
nature  of  their  operations ;  these  being  carried  on  under 
the  guidance  perhaps  of  one,  and  rarely  of  more  than  two, 
really  potential  Sense  Endowments.  The  power  shown  by 
these  organisms  of  adapting  their  actions  to  new  condi- 
tions with  which  they  were  brought  face  to  face,  was  found 
to  be  very  slight  and  almost  wanting. 

Reference  has  also  been  made  to  the  instincts  of  Birds, 
to  the  wider  range  of  mental  phenomena  displayed  by 
these  animals,  as  well  as  to  their  greater  power  of  adapt- 
ing their  actions  to  the  exigencies  of  new  conditions. 
The  nervous  system  of  Birds  is,  however,  much  more 
highly  developed  than  that  of  Insects,  as  is  evidenced 
more  especially  by  their  possession  of  large  Cerebral  Lobes 
for  the  correlation  of  sensorial  impressions.  Birds  are, 
moreover,  commonly  guided  by  three  highly  acute  Sense 
Endowments  instead  of  two,  in  addition  to  others  of  minor 
importance. 

Our  consideration  of  the  actions  of  Birds  afforded  good 
warrant  for  the  inference  that  in  them  the  germs,  or  some- 
times rather  more  than  the  germs,  of  higher  mental 
manifestations  may  become  nascent  in  the  form  of  rudi- 


808  THE    MENTAL    CAPACITIES    ANT> 

mentavy   Thoughts,    or    more   developed   Emotions    and 
VcHtions. 

The  survey  since  taken  of  some  of  the  principal  forms 
of  the  Brain  in  Quadrupeds  and  Quadrumana  reveals  a 
very  marked  increase  in  the  relative  size  and  complexity 
of  the  Cerehral  Hemispheres  in  each  of  these  great  classes. 
And  though  no  distinct  serial  order  is  to  be  traced,  it 
must  be  obvious  from  the  preceding  descriptions  and 
figures,  that  the  brain  of  the  higher  Apes  presents  almost 
as  great  an  advance  in  relative  size  and  complexity  over 
that  of  the  higher  Quadrupeds,  as  that  which  characteiizes 
the  brain  of  these  latter  animals  in  comparison  with  the 
brain  of  Birds. 

It  remains,  therefore,  briefly  to  consider  the  scope  of 
the  mental  life  of  Quadrupeds  and  Quadrumana  for  com- 
parison with  that  of  Birds.  The  materials  for  arriving  at  a 
judgment  upon  this  point  must  still  be  of  the  same  order 
as  they  were  in  the  case  of  animals  lower  in  the  scale  of 
organization.  We  can  only  study  their  actions  in  the 
records  which  have  been  given  of  them,  striving  to  inter- 
pret them  in  the  manner  previously  indicated  (p.  106)  by 
the  reflected  light  derived  from  our  knowledge  of  human 
intelligence  and  human  actions — and  yet  not  too  much 
from  the  mere  human  point  of  view. 

It  is  worth  while  here  to  take  note  of  the  fact  that 
the  most  intelligent  Quadrupeds — and  more  especially 
Elephants — have  the  advantage  of  bringing  into  play  a 
rather  highly  developed  sense  of  Touch,  in  aid  of  their 
other  acute  and  highly  discriminative  senses  of  Sight, 
Smell,  and  Hearing ;  and  also  that  the  same  four  sen- 
sorial endowments  are  commonly  in  active  operation 
among  Quadrumana — although  with  them  Smell  seems 
to  diminish  in  importance,  while  the  more  definite  and 


CiJAP.  XVriT.]      POWERS    OF    HIGHER    BRUTES.  f.OD 

intellectual  sense  of  Touch  becomes  more  and  more  called 
into  play,  as  it  is  with  human  beings. 

In  Chapter  XII.  it  has  been  shown  that  Intelligence 
or  Keason,  as  well  as  Emotion,  have  their  roots  in,  and 
cannot  be  separated  from,  Sensorial  Activity ;  and  it  has 
also  been  shown  (pp.  187-191)  that  the  sensorial  endow- 
ments and  mental  attainments,  such  as  they  are,  of  all 
animals  whatsoever  tend  to  be  transmitted  in  a  constant 
and  truly  marvellous  manner  to  their  oflspring. 

The  question  of  the  number  and  the  excellence  of  the 
Sense  Endowments  of  particular  kinds  of  animals  is,  there- 
fore, of  considerable  importance  in  relation  to  the  degree 
of  their  IiitclHgence.  Each  practically  new  addition  or 
greatly  developed  activity  of  this  kind,  in  animals  whose 
intelligence  is  so  far  developed  as  to  be  obvious  and 
indubitable,  cannot  fail  to  give  additional  breadth  and 
strength  to  their  mental  operations — to  say  nothing  of  the 
new  special  knowledge,  resulting  from  its  exercise,  as  to 
the  qualities  of  the  outer  world  of  things  by  which  such 
organisms  are  surrounded. 

Gradually  altering  race  experiences,  if  persistent  enough, 
are  certain  to  leave  their  marks  in  the  form  of  minute  struc- 
tural modifications  of  the  Nervous  System — and  these, 
if  not  actually  recognizable  in  themselves,  reveal  them- 
selves by  their  effects — that  is,  by  the  manifestation  on  the 
part  of  such  animals  of  new  or  altered  susceptibilities  to 
Impressions  from  external  things  or  occurrenccis.  It  is  a 
familiar  fact  that  disuse  blunts  the  sensorial  powers  of 
individual  animals,  while  use  and  exercise  tend  to  sharpen 
them.  We  can  easily  imagine,  therefore,  what  potent 
modifiers  '  use '  and  '  disuse '  may  be  when  they  bear  respec- 
tively upon  the  same  Sense  Endowments  for  generation 
after  generation  of  some  particular  kind  of  animal. 

Inasmuch  as  nothing  like  a  single  serial  progression  is 


810  THE    MENTAL    CAPACITIES    AND 

to  be  traced  among  animals  now  extant,  or  even  when  these 
are  intercalated  with  the  remains  of  the  very  small  frac- 
tion of  extinct  forms  which  have  as  yet  been  discovered  in 
the  shape  of  fossil  relics,  so  nothing  like  a  mental  serial 
progression  is  to  be  looked  for.  Whatever  the  grade  oi 
organization  of  an  animal  may  be,  we  have,  in  estimating 
the  nature  of  its  mental  processes  and  powers,  to  look 
much  to  its  present  sensorial  organization  and  endow- 
ments. It  is  true,  however,  that  the  experiences  of 
ancestral  forms  will  have  had  much  to  do  with  the  basis 
and  background  of  the  creature's  Mental  Processes,  both 
in  special  and  in  general  directions. 

If  the  Mole  and  its  ancestors,  owing  to  their  usual  con- 
ditions of  life,  have  had  little  need  of  eyes,  and  these  have 
consequently,  in  the  course  of  generations,  undergone  a 
process  of  atrophy  from  disuse,  the  basis  of  the  mental 
processes  of  these  particular  animals  must  have  been 
thereby  proportionately  altered.  Sight  impressions  being 
cut  off,  other  Sensorial  Endowments  would  have  gradually 
risen  in  importance  for  the  daily  conduct  of  their  life. 
The  sum  total  of  the  neural  impressions  and  responses 
of  such  animals  would,  therefore,  come  to  be  very  different 
from  those  of  their  near  ally,  the  keen-visioned  Rat.  How 
different,  again,  must  be  the  web  of  sensorial  impressions 
constituting  the  basis  of  the  mental  life  of  the  Stag,  into 
which  Scents  enter  so  largely,  when  compared  with  that 
of  the  Whale,  the  Porpoise,  or  the  Dolphin,  in  whom 
impressions  of  this  order  seem  to  be  almost  or  wholly 
wanting. 

While  there  may,  therefore,  be  a  general  onward  pro- 
gress in  the  complexity  of  mental  phenomena  in  different 
groups  of  animals,  regarded  as  groups,  this  general  ad- 
vance may  be  strangely  chequered  and  interrupted,  if  we 
look  at  its  manifestations  in  individual  forms,  owing  to 


Cmap.  XVill.]      POWEllS    OP    HIGHER    BRUTES.  311 

the  peculiar  habits  of  eadi,  and  the  consequently  varying 
nature  of  their  sense  endowments — either  in  the  direc- 
tion of  defect  or  of  hyper-refinement  in  discriminative 
power. 

The  space  available  in  this  volume  is  wholly  inadequate 
to  permit  of  any  attempt  to  do  more  than  call  the  reader's 
attention  to  a  few  of  the  more  important  of  the  recorded 
actions  of  some  of  the  most  intelligent  of  Quadrupeds  and 
Quadrumana.  These,  however,  may  be  useful  for  com- 
parison with  those  recorded  in  previous  chapters  concern- 
ing animals  lower  in  the  scale  of  development. 

The  instinctive  operations  of  Beavers  are  both  well- 
known  and  remarkable.  While  they  show  us  a  much  less 
machine-like  series  of  actions  than  are  exhibited  by  In- 
sects, Beavers  also  display  a  more  distinct  power  of 
adaptation  to  new  or  unusual  conditions  than  is  to  be 
met  with  among  Birds.  They  live  in  colonies,  and  work 
together  in  a  most  skilful  manner  to  bring  about,  by 
numerous  and  complicated  means,  some  common  purpose 
— a  purpose,  moreover,  which  has  at  different  times  to  be 
executed  under  by  no  means  identical  conditions.  As 
Leuret*  points  out,  so  great  a  variety  of  labours  is  needed 
for  the  constructions  carried  on  by  the  Beaver;  they  in- 
clude so  many  instances  of  a  well-made  choice ;  so  many 
accidental  difficulties  are  surmounted  by  these  animals, 
that  it  is  impossible  not  to  recognize  in  their  acts 
the  characteristics  of  a  rather  high  intelligence — even 
though  it  may  be  of  instinctive  origin.  The  fact  of  their 
intelligence  having  this  basis  does  not,  however,  detract  in 
the  least  from  its  dignity  and  importance,  seeing  that 
instinctive  operations  constitute  almost  the  necessary 
Btarting-point  for  that  freer  play  of  choice  and  independent 

•'  Aiiat.  Comp.  du  Syst.  Nerv."  t  i.  1839,  p.  506. 


312  THE    MENTAL    CAPACITIES    AND 

adaptation  of  means  to  ends  which  characterizes  Intelli- 
gence in  all  its  grades. 

The  sagacity  of  the  Horse  and  of  the  Dog — and  espe- 
cially of  the  latter — is  well  known  and  appreciated.  Much 
of  the  high  intelligence  exhibited  by  Dogs,  however,  is 
perhaps  to  be  regarded  as  a  distinct  result  of  the  educa- 
tion of  individual  animals  while  they  have  been  acting  as 
Man's  associates  and  helpers.  Under  his  influence  the 
aptitudes  and  cerebral  organization  of  the  race  appear  to 
have  been  slowly  improved.  Still,  notwithstanding  the 
advantages  of  this  association,  the  Dog  could  never  have 
profited  by  it  so  much  as  he  has  done,  had  he  not  been 
endowed  with  an  unusual  plasticity  of  organization,  to- 
gether with  faculties  of  observation  and  a  power  of  Atten- 
tion of  no  ordinary  kind. 

The  faculties  of  the  Wild  Dog  are  not  very  different 
from  those  of  the  Wolf,  and  in  almost  all  respects  they  are 
notably  inferior  to  those  of  animals  whose  ancestors  have 
been  educated  by  association  with  Man.  Even  Wolves 
will,  however,  hunt  their  prey  in  couples  with  skilfully 
concerted  though  varying  actions,  calculated  to  make  their 
victims  fall  an  easy  prey  to  stratagem.  Dogs  have  also 
been  known  to  adopt  a  very  similar  role — and  that  even 
when  the  conspirators  have  been  altogether  different  in 
size  and  breed. 

Evidence  is  not  wanting  to  show  that  some  of  the 
emotions  of  a  Dog  may  have  an  altruistic  basis — apart 
from  mere  instinctive  love  or  affection  for  their  offspring. 
The  Dog's  sympathy  with  its  master  when  in  distress,  is 
more  marked  and  more  frequently  met  with  than  it  is 
for  members  of  its  own  kind  whom  it  may  chance  to 
meet  under  circumstances  of  more  or  less  distress.  Of 
the  former  kind  of  Sympathy  on  the  part  of  the  Dog 
numerous  stories  are  on  record;  and  this  feeling  is  to  be 


Chap.  XYIIL]      POWERS    OF    HIGHER    BRUTES.  313 

regarded  as  the  joint  product  of  the  animars  intelligence 
and  of  its  love  for  its  master  or  mistress.  Of  the  mani- 
festations of  s^^mpathy  for  their  own  kind  the  records  are 
comparatively  scarce.  Swainson,  however,  quotes  a  good 
instance  of  it.     He  says*  :  — 

"The  Eev.   Mr.    S ,   of  M ,   Denbighshire,  had  a 

favourite  ISTewfoundland  dog,  who  lived  at  large,  partook  of 
the  best  of  everything,  and  exercised  his  power  with  great  mild- 
ness. He  was  seen  more  than  once  leaping  the  gate  which 
separated  the  yard  of  the  honse  from  the  farm-yard,  and  carrying 
large  bones  that  had  been  given  him  to  a  sporting  dog,  who  was 
tied  up  in  the  stable." 

The  occasional  dislike  of  the  Dog  for  members  of  its 
own  species — engendered  almost  at  first  sight — is  some- 
times striking  enough  in  itself,  but  when  we  find  that  a 
memory  of  this  sort  of  Emotion  is  retained,  and  roused 
again  after  a  long  period  by  a  simple  Association  of  Ideas 
" — roiised,  too,  in  such  force  as  to  stimulate  to  immediate 
action — the  fact  is  one  which  deserves  to  be  recorded  in 
illustration  of  the  mental  and  emotional  processes  of  the 
Dog.  Dr.  Paladilhe,  of  Montpelier,  has  cited  an  inter- 
esting instance  of  this  kind.  Being  about  to  spend  some 
days  with  relatives  living  in  a  small  village  about  twenty- 
two  miles  distant,  he  took  his  greyhound  with  him,  she 
never  having  been  there  before. 

"  It  so  happened,"  he  says,t  "  that  not  far  off  there  was  a  hound 
bitch  belonging  to  one  of  my  cousin's  neighbours,  and  between  these 
two  animals  (from  the  beginning  of  my  short  stay)  there  arose  the 
deepest  hatred  and  animosity,  and  conflicts  of  the  most  ferocious 
kind  were  matters  of  daily,  almost  hourly,  occurrence.  Time 
altogether  failed  in  producing  any  better  feeling  between  them,  and 
to  the  end  of  my  visit  each  was  ever  ready  and  anxious  to  try  its 

♦  "  Habits  and  Instincts  of  Animals,"  p.  72. 
t  "  Nature,"  August  7,  1873. 


314  THE    MENTAL    CAPACITIES    AND 

etrength  whenever  the  opportunity  offered.  In  the  course  of  the 
following  year  I  paid  a  second  visit  to  the  same  place  accompanied 
by  my  greyhound,  and  about  three-quarters  of  an  hour  betore  I 
reached  the  village,  the  animal,  as  if  struck  with  a  sudden  idea, 
rushed  forward  at  her  full  speed,  and  all  attempts  to  call  her  back 
proved  quite  ineffectual.  On  reaching  the  village  I  found  that  a 
terrible  encounter  had  already  taken  place  between  the  two  heroines, 
who  were  on  the  point  of  renewing  the  attack  after  a  temporary- 
cessation  of  hostilities." 

Some  Dogs  seem  even  to  entertain  an  embryo  notion  of 
*  justice '  and  its  opposite,  the  realization  of  which  testifies 
to  the  occurrence  of  mental  processes  of  some  complexity 
for  such  animals.     Leuret  cites  the  following  anecdote  : — 

"  Arago,  the  astronomer,  was  once  overtaken  by  a  storm  in  a 
small  village  in  the  south  of  France,  and  Bureau  de  Lamalle,  who 
related  the  story  ('Ann.  des  Sc.  Nat.'  t.  xxii.  1831),  says  tho 
cottagers  with  whom  he  had  taken  refuge  could  only  offer  him  a 
chicken  for  dinner — and  this  he  at  once  ordered  to  be  co  jked.  The 
spit  was  provided  with  a  revolving  drum,  into  which  a  dog  was 
accustomed  to  enter  in  order  to  give  it  the  necessary  movement. 
One  of  the  dogs  kept  for  this  purpose  ('  turnspits  '  as  they  were 
called)  was  in  the  kitchen,  and  on  the  cottager  attempting  to  take 
it,  the  dog  showed  his  teeth,  hid  himself,  and  obstinately  disobeyed 
his  master's  orders.  Arago,  in  surprise,  asked  the  cause,  and  was 
told  that  the  dog  rebelled  because  it  was  his  companion's  turn. 
The  astronomer  directed  that  the  other  dog  should  be  fetched,  and 
on  its  arrival,  at  the  first  sign  from  his  master,  it  went  into  the 
drum  and  turned  the  spit  for  about  ten  minutes.  In  view  of 
completing  the  experiment,  Arago  caused  the  drum  to  be  stopped 
and  the  dog  liberated,  telling  the  cottager  then  to  summon  the 
previously  restive  animal.  The  order  was  given,  and  the  animal 
whose  refusal  had  previously  been  so  obstinate,  convinced  that  his 
turn  of  drudgery  had  come,  entered  the  drum  of  his  own  accord, 
and  began  to  turn  it." 

Those  who  have  kept  intelligent  dogs  know  the  sur- 
prising extent  to  which  they  become  capable  of  under- 
standing language — that  is  their  power  of  comprehending 
and  of  acting  upon   mere  verbal    instructions.     A   good 


Crap.  XVIII.]      POWERS    OF    HIGHER    BRUTES.  815 

instance  of   this  has  lately  been   cited   by  Mr.  Charles 
Stewart,  of  Tighnduin,  Perthshire.     He  says  : —  * 

"  A  few  years  ago  I  kept  a  collie  dog  named  '  Bodach '  at  my 
farm,  for  herding  the  milk  cows,  and  who  recognized  the  dairymaid 
as  his  mistress.  On  her  directing  him  to  keep  the  cows  on  a  cer- 
tain part  of  a  field,  he  would  lay  himself  down  in  the  centre  ot  a 
line  fixed  by  him  as  the  proper  limit.  Patiently  and  vigilantly  he 
■would  remain  in  quietness,  until  any  of  the  cows  passed  his  limit, 
when  he  would  swoop  down  on  the  trespasser,  take  her  by  the 
heels,  and  drive  her  back.  It  was  wonderful  in  how  short  a  time 
the  cows  came  to  recognize  and  respect  the  arrangement.  He  also 
came  to  know  some  of  the  cows  by  name.  One  of  them  named 
'  A ggi' required  at  certain  seasons  to  be  milked  oftener  than  the 
others,  and  the  dairymaid  had  only  to  say  in  Gaelic,  '  Bodach,  go 
and  bring  home  Aggi,'  when  he  would  start  for  the  pasture,  single 
out  Aggi,  and  bring  her  carefully  home." 

The  cunning  of  the  Fox  is  proverbial,  and  often  charac- 
terized by  a  degree  ot  intelligence  which  is  not  a  littla 
remarkable,  when  we  consider  that  it  is  altogether  the 
result  of  the  creature's  unaided  converse  with  Nature — - 
and  certainly  independent  of  any  encouragement  from 
Man.  A  good  example  of  this  native  intelligence  is  to 
be  found  in  the  following  incidents  t  :— 

"A  farmer  looking  out  of  his  window  one  summer's  morning 
about  three  o'clock  saw  a  fox  crossing  a  field  before  it,  carrying  a 
large  duck  that  he  had  captured.  On  coming  to  a  stone  dyke 
about  four  feet  high,  on  the  side  of  the  field,  Reynard  made 
an  effort  to  leap  over  it  with  his  prey,  but  failed,  and  fell 
back  into  the  field.  After  making  three  attempts  with  the 
same  result  he  sat  down  and  viewed  the  dyke  for  a  few  minutes ; 
after  apparently  satisfying  himself,  he  caught  the  duck  by  the 
head,  and  standing  up  against  the  dyke  with  his  fore-paws,  as  high 

*  "  Nature,"  May  1,  1879,  p.  21 ;  another  excellent  illustration 
of  the  intelligence  of  a  dog  is  given  in  "  Nature,"  March  20,  1879, 
p.  458. 

t "  Nature,"  March  27,  1873,  p.  410 ;  February  27,  1879,  p.  385 ; 
and  March  6,  1879,  p.  409. 


316  THE    MENTAL    CAPACITIES    AND 

as  he  could  reach,  he  placed  the  bill  of  the  duck  in-  a  crevice  in  tht? 
wall;  then  springing  upon  the  top,  he  reached  down,  and  pulling 
up  the  duck  dropped  it  upon  the  other  side,  leaped  down,  and,  pick- 
ing it  up,  went  on  his  way." 

The  Rev.  G.  Henslow  writes  thus  : — ■ 

"  The  Arctic  fox — too  wary  to  be  shot  like  the  first  who  took  a 
bait  tied  to  a  string,  which  was  attached  to  the  trigger  of  a  gun — 
would  dive  under  the  snow  and  so  pull  the  bait  down  below  the 
line  of  fire."  Dr.  John  Kay  adds  that  he  has  known  several  cases 
in  which,  under  such  conditions,  instead  of  digging  and  jumping 
into  a  trench  in  the  snow  to  avoid  the  shot,  an  Arctic  fox  has  "  cut 
the  line  attaching  the  bait  to  the  trigger  of  the  gun  before  taking 
the  bait." 

The  large  and  highly  convoluted  brains  of  the  Porpoise 
and  of  the  Dolphin,  as  well  as  those  of  many  marine  Car- 
nivores, have  long  been  deemed  remarkable  peculiarities 
in  these  animals  ;  and  doubts  have  been  expressed  whether 
their  Mental  Faculties  are  in  any  way  equal  to  what  might 
have  been  expected  if  we  look  merely  to  the  size  and  de- 
velopment of  their  Cerebral  Hemispheres.  Some  remarks 
have  already  been  made  on  this  subject,  with  the  view 
of  showing  that  the  extraordinary  activity  and  varied 
muscular  movements  of  these  creatures  may  have  much 
to  do  with  the  great  size  even  of  the  Cerebral  Hemispheres, 
as  it  has  unquestionably  to  do  with  the  great  develop- 
ment of  the  Cerebellum.*  Their  voracity  is  enormous  ; 
and  this,  together  with  the  rapidity  and  variety  of  their 
movements,  must  entail  a  corresponding  activity  of  all 
their  Sensorial  Organs.  The  diversity  of  their  daily  ex- 
periences also  is  probably  greatly  increased  by  the  fact  tbat 
they  are  gregarious  animals,  accustomed  to  hunt  their  prey 
and  live  together  in  small  troops.  It  is  quite  possible, 
therefore,  that  the  s^agacity  and  emotional  nature  of  those 
♦  Sec  p.  278. 


Chap.  XYIII.]      PO^VERS    OF    HIGHER    BRUTES.  317 

animals  may  be  much  more  liighly  developed  than  is  gene- 
rally imagined. 

But  we,. unfortunately,  know  very  little  about  the  more 
intimate  habits  of  either  Porpoises  or  Dolphins,  as  the 
medium  in  which  they  live  removes  them  so  much  from  any 
minute  and  continuous  examination.  Some  few  interesting 
observations  have,  however,  been  recorded  concerning  two 
Porj^oises  formerly  in  the  large  tank  of  the  Brighton 
Aquarium. 

W.  Saville  Kent  says:  * — "The  first  comer  so  readily  accommo- 
dated itself  to  its  altered  conditions,  that  on  the  second  day  it  took 
its  food,  smelts  and  sprats,  from  its  keeper's  haud,  and  has  con- 
tinued to  do  so  ever  since.  The  later  arrival  was  at  first  less 
sociably  inclined,  but  both  have  latterly  become  equally  tame,  and 
frequently,  while  receiving  fish  from  my  hand  with  the  gentleness  of 
pet  dogs,  have  pernjitted  me  to  pat  and  stroke  their  slippery  india- 
rubber  like  backs." 

Curiosity  is  a  sign  of  Intelligence  of  a  comparatively 
high  order.  It  may  be  said  to  be  almost  absent  in  Birds, 
but  it  seems  to  exist  to  a  very  marked  degree  in  the 
Porpoise. 

W.  Saville  Kent  says  : — "A  new  arrival  is  at  once  subjected  to 
the  most  importunate  attention,  and,  advancing  from  familiarity  to 
contempt,  if  disapproved  of,  soon  becomes  the  object  of  attack  and 
persecution.  A  few  Dog-fish,  three  or  four  feet  long,  placed  in  the 
same  tank,  soon  fell  victims  to  the  tyranny  cf  the  Porpoises;  and 
a  fine  Sturgeon,  six  feet  long,  was  likewise  much  persecuted  and 
had  to  be  removed.  This  was  also  the  case  with  some  large  Skates. 
The  latter,  so  long  as  they  maintained  their  usual  habit  of  lying 
sluggishly  on  the  floor  of  the  tank,  escaped  molehtatiou ;  but  no 
sooner  did  these  fish  display  any  unwonted  activity  than  the 
Porpoises  were  upon  them,  and,  making  a  convenient  handle  of 
their  characteristic  attenuated  tails,  worried  them  incessantly." 
On  one  occasion,  the  same  observer  witnessed  "  the  two  Cetacea 
acting  evidently  in  concert  against  one  of  the  Skates." 

♦"Nature,"  July  17,  1873,  p.  223. 


318  THE    MENTAL    CAPACITIES    AND 

Porpoises  make  a  prodigious  slaughter  among  the  shoals 
of  Herring,  Mackerel,  and  other  fish  which  periodically 
visit  our  coasts. 

As  to  the  Dolphin  we  have  no  precise  knowledge, 
but  many  stories  have  come  down  to  us  from  ancient 
times,  the  general  purport  of  which  seems  to  testify  to  their 
rare  docility,  intelligence,  and  sympathetic  nature.  Fact 
and  fable  may  be  here  inextricably  intermixed,  though,  as 
Leuret  suggests,  it  seems  probable  that  there  is  some 
basis  of  truth  for  these  various  stories.  We  stand  much 
in  need,  however,  of  some  accurate  modern  observations 
as  to  the  habits  and  degree  of  Intelligence  of  these  highly 
interesting  creatures,  whose  brain  is  so  large  and  well 
developed.  Swainson  quotes  Cuvier,  to  the  effect  that 
the  Dolphin  "carefully  suckles  and  tends  its  young, 
carrying  them  gently  under  its  pectoral  fins,  sporting 
with  and  continuously  exercising  them  in  swimming. 
The  male  also  attaches  himself  for  life  to  his  female 
companion,  and  becomes  her  most  zealous  guardian  and 
protector." 

The  Elephant  is,  by  general  consent,  regarded  as  the 
most  sagacious  of  all  four-footed  beasts  living  in  a  state 
of  nature.  It  seems  pretty  certain,  however,  that  this 
estimate  would  not  be  applicable  to  brutes  generally,  in- 
clusive of  the  Quadrumana. 

Like  the  Apes,  the  Elephant  adds  to  its  other  sensorial 
endowments  an  acute  and  discriminative  sense  of  Touch. 
Its  prehensile  trunk  serves  all  the  purposes  to  which  a 
highly  sensitive  hand  could  be  applied.  The  Elephant 
enjoys  the  further  very  considerable  advantage  resulting 
from  a  prolonged  length  of  life.  When  an  animal  which 
already,  in  its  early  days,  possesses  a  fair  amount  of  intelli- 
gence, has  its  experiences  extended  over  a  period  so  con- 
siderable as  150  years  or  more,  we  have  a  right  to  expect 


CiiAP.  XYIIL]      POWERS    OF    HIGHER    BRUTES.  819 

that  individuals,  and  ultimately  the  race,  should  benefit 
much  therefrom  in  the  way  of  increased  sagacity.  The 
importance  of  this  point  will  be  best  appreciated  by  those 
who  know  the  differences  in  point  of  Sagacity  between  the 
generality  of  young  dogs  and  those  that  have  lived  on  to 
their  full  term  of  active  life.  For,  if  so  much  difference  in 
this  respect  arises  with  the  Dog  in  the  course  of  eight  or 
ten  years,  we  may  naturally  look  for  notably  greater 
effects  of  the  same  kind  during  a  life  at  least  ten  times 
as  long  as  that  of  the  Dog. 

On  the  other  hand,  it  must  not  be  forgotten  that  the 
Elephant  never  breeds  in  captivity,  and  therefore  never, 
like  the  Dog,  bequeaths  to  succeeding  generations  any  of 
those  higher  developments  of  its  faculties  and  powers  which 
may  have  resulted  from  its  intercourse  with,  and  education 
by,  human  associates.  The  individual  Elephant,  there- 
fore, can  be  educated  by  man,  but  the  race  must  have  its 
faculties  sharpened  in  the  wider  school  presented  by  the 
sum-total  of  their  own  natural  surroundings. 

When  once  tamed,  the  Elephant  becomes,  as  Buffon 
says,  the  most  tractal)le  and  submissive  of  all  animals  : — 

"  He  is  affectionate  to  his  keeper,  caresses  him  and  does  what- 
ever he  can  to  please  him.  In  a  little  time  he  understands 
signs,  and  even  the  expression  of  sounds;  he  distinguishes  the  tone 
of  command,  that  of  anger  or  goodnature,  and  acts  accordingly. 
He  never  mistakes  the  words  of  his  master;  he  receives  his  oraers 
with  attention,  and  executes  them  with  prudence  and  eagerness." 

The  intelligence  and  sagacity  which  the  Elephant  is 
well  known  to  display,  in  aid  of  his  keepers,  in  capturing 
sauns  or  solitary  males  in  the  wild  state,  as  quoted  by 
Swainson,*  is  so  surprising  as  to  be  almost  incredible, 
were  it  not  that  the  facts  are  notoriously  well  attested. 
The  account  is  too  long  to  be  here  quoted. 

•  "Habits  and  Instincts  of  Anin.als,"  p.  24. 


320  THE    MENTAL    CAPACITIES   AND 

The  same  kind  of  judgment  and  sagacity  are,  however, 
shown  by  the  Elephant  when  he  gets  into  too  soft  a 
swamp. 

Swainson  writes: — "The  cylindrical  form  of  an  Elephant's  leg— 
which  is  nearly  of  equal  thickness — causes  the  animal  to  sink  very 
deep  in  heavy  ground,  especially  in  the  muddy  banks  of  small 
rivers.  When  thus  situated,  the  animal  will  endeavour  to  lie  on 
his  side,  so  as  to  avoid  sinking  deeper;  and,  for  this  purpose,  will 
avail  himself  of  every  means  to  obtain  relief.  The  usual  mode  of 
extricatir)g  him  is  much  the  same  as  when  he  is  pitted ;  that  is, 
by  supplying  him  liberally  with  straw,  boughs,  grass,  &c. ;  these 
materials  being  thrown  to  the  distressed  animal  he  forces  them 
down  with  his  trunk,  till  they  are  lodged  under  his  fore-feet  in 
sufficient  quantity  to  resist  his  pressure.  Having  thus  formed  a 
sulHcient  basis  for  exertion,  the  sagacious  animal  next  proceeds  to 
thrust  other  bundles  under  his  belly,  and  as  far  back  under  his 
flanks  as  he  can  reach;  when  such  a  basis  is  formed  as  ma}'-  be,  in 
his  mind,  proper  to  proceed  upon,  he  throws  his  whole  weight  for- 
wards, and  gets  his  hind  feet  gradually  upon  the  straw,  &c.  Being 
once  confirmed  on  a  solid  footing,  he  will  next  place  the  succeeding 
bundles  before  him,  pressing  them  well  with  his  trunk,  so  as  to  form 
a  causeway  by  which  to  reach  the  firm  ground."  "  He  will  not  bear 
any  weight,  definitely,  until  by  trial  both  with  his  trunk  and  the 
next  foot  that  is  to  be  planted,  he  has  completely  satisfied  himself 

of  the  firmness  of  the  ground  he  is  to  tread   upon The 

anxiety  of  the  animal,  when  bemired,  forms  a  strong  contrast  with 
the  pleasure  he  so  strongly  evinces  on  arriving  at  terra  firina." 

The  following  particulars  were  among  those  reported  to 
the  Academy  of  Sciences,  concerning  a  young  animal, 
the  property  of  Louis  XIV.,  which  was  kept  for  a  time 
at  Versailles  : — 

"  The  Elephant  seemed  to  discern  when  anybody  made  a  fool  of 
him  ;  and  he  remembered  the  afi:ront,  to  be  revenged  of  it  at  the 
first  opportunity.  Having  been  baulked  by  a  man  who  feigned  to 
throw  something  into  his  mouth,  he  struck  him  with  his  trunk  and 
broke  two  of  his  ribs,  afterwards  he  trampled  him  under  his 
feet. A   painter   was   desirous   of    sketching   him   in   an 


Chap.  XVIII. ]      POWERS    OF    HIGHER    BRUTES-  321 

extroordinary  attitude,  that  is  witli  his  truuk  erect  and  month  open. 
The  servant  of  the  painter  to  make  him  retain  that  attitude  threw 
fruits  into  his  mouth ;  but  afterwards  he  deceived  him,  which  pro- 
voked the  elephant's  indignation  ;  and,  as  if  he  had  known  that 
tiie  cause  of  this  deception  was  the  painter's  desire  of  having  him 
drawn,  he  revenged  himself  on  the  master  by  throwing  with  his 
trunk  a  great  quantity  of  water,  whicli  spoiled  the  paper  intended 
for  his  desigr." 

As  a  well-authenticated  instance  of  the  Memory  of  the 
Elephant,  and  of  his  obedience  to  his  keeper,  Swainson 
gives  the  following  story  recorded  by  Captain  Williamson, 
and  attested  by  the  signatures  of  several  persons  who 
were  witnesses  of  the  occurrence: — 

"  An  Elephant  that  had  been  some  years  domesticated  got  loose 
during  a  stormy  night,  and  rambled  into  his  native  jungles.  Abet 
four  years  afterwards,  when  a  large  drove  had  been  captured  in  the 
*  keddali,'  the  keeper  of  the  lost  one,  along  with  others  of  the  natives, 
had  ascended  the  barricade  of  timber  by  which  it  was  surrounded, 
to  inspect  the  new  guests;  among  them  he  fancied  he  recognized 
his  former  charge,  and,  though  ridiculed  by  his  comrades,  he  called 
to  the  elephant  in  question  by  the  name  which  it  had  formerly 
borne.  To  the  wonder  of  all  present  the  animal  came  towards 
him.  The  man,  overjoyed  at  the  event,  got  over  the  barrier,  and 
ordering  the  elephant  to  lie  down  to  be  mounted,  he  bestrode 
its  neck  as  in  former  times  and  exultingly  led  it  forth,  to  the 
admiration  and  surprise  of  all  present." 

With  Memory  such  as  this,  with  a  power  of  fixing  its 
Attention,  with  a  plastic  nervous  system,  and  with  a  very 
long  life  for  each  individual,  the  remarkable  Sagacity  of 
these  animals  may  be  in  a  measure  understood. 

High,  however,  as  is  the  Intelligence  of  the  Elephant, 
it  is  unquestionably  much  below  that  of  many  of  the 
Quadrumana — even  of  some  whose  zoological  status  is 
inferior  to  that  of  the  great  '  man-like  '  Apes.  Who,  that 
has  watched  any  of  these  creatures,  does  not  know  their 
varied    powers    of    appreciating    the    conditions    around 


322  THE    MExXTAL    CAPACITIES    AND 

them,  and  of  shaping  their  actions  into  some  accordance 
therewith — as  well  as  the  range  and  complexity  of  the 
Emotions  which  they  are  capable  of  feeling  and  plainl}' 
manifesting  on  different  occasions. 

In  regard  to  the  Cai,  or  Weeper  Capuchin,  one  of  the 
long-tailed  New  World  Monkeys, — 

P.  M.  Duncan  (Cassell's  " Nat.  History,"  p.  184)  quotes  Renorgror 
to  the  effect,  that  when  he  first  gave  eggs  to  these  animals  "they 
smashed  them,  and  thus  lost  much  of  their  contents;  afterwards  they 
gently  put  one  end  against  some  hard  body  and  picked  off  the  bits 
of  shell  with  their  fingers.  After  cutting  themselves  only  once  with 
a  sharp  tool  they  would  not  touch  it  again,  or  would  har.dle  it  with 
the  greatest  care.  Jjumps  of  sugar  were  often  given  them  wrapped 
up  in  paper,  and  Rengger  sometimes  put  a  live  wasp  in  the  paper. 
After  this  had  happened  once,  they  always  first  held  the  packet  to 
their  ears  to  detect  any  movement  within." 

The  same  writer  in  his  account  of  a  female  Chacma, 
or  Pig-tailed  Baboon  (loc.  cit.,  p.  146),  says  : — 

"  She  not  only  adopted  young  Monkeys  of  other  species, 
but  stole  young  dogs  and  cats,  which  she  continually  carried 
about.  Her  kindness,  however,  did  not  go  so  far  as  to  share  her 
food  with  her  adopted  ofF^pring.  An  adopted  kitten  scratched  this 
affectionate  and  selfish  old  thing,  who  certainly  had  a  fine  intellect, 
for  she  was  much  astonished  at  being  scratched,  and  immediately 
examined  the  kitten's  feet,  and  without  more  ado  bit  off  the  claws  I  ** 

The  same  writer  also  cites  (loc.  cit.,  p.  184,)  the  follow- 
ing remarkable  instance  of  Intelligence  : — 

*'  Formerly  one  of  the  large  Monkeys  in  the  Zoological  Gardens 
had  weak  teeth,  and  he  used  to  break  open  the  nuts  with  a  stone. 
Mr.  Darwin  was  assured  by  the  keepers  that  this  animal,  after 
using  the  stone  hid  it  in  the  straw,  and  would  not  let  any  other 
Monkey  touch  it." 

The  development  of  Intelligence,  Emotion,  and  Voli- 
tion, which  becomes  so  obvious  in  lower  Quadrumana, 


Chap.  XVIII.]      POWERS    OF    HIGHER    BRUTES  323 

is,  however,  recognizable  in  a  still  more  striking  degree, 
when  we  come  to  the  so-called  *  man-like  '  Apes,  viz.,  the 
Gibbons,  the  Chimpanzee,  the  Gorilla,  and  the  Orang- 
utan, as  a  few  details  will  show. 

A  writer  in  "  Nature  "  (Jan.  29,  1874)  says  : — 

"  I  keep  in  mj  garden  a  number  of  Gibbon  aipes  {Hylolates  agilis) ; 
tliey  live  quite  free  from  all  restraint  in  the  trees,  merely  coming  when 
called  to  be  fed.  One  of  these,  a  yonng  male,  on  one  occasion  fell  from 
a  tree  and  dislocated  his  wrist;  it  received  the  greatest  attention 
from  the  others,  especially  from  an  old  female,  who,  however,  was 
no  relation ;  she  used,  before  eating  her  own  plantains,  to  take 
up  the  first  that  were  offered  to  her  every  day  and  give  them  to 
the  cripple,  who  was  living  in  the  eaves  of  a  wooden  house ;  and 
I  have  frequently  noticed  that  a  cry  of  fright,  pain  or  distress  from, 
one,  would  bring  all  the  others  at  once  to  the  complainer,  and  they 
would  then  condole  with  him  and  fold  him  in  their  arms." 

Concerning  the  largest  of  the  Gibbons,  the  Siamang,  a 
native  of  Sumatra,  some  interesting  details  have  been 
given  by  G.  Bennett,*  of  an  animal  which  he  brought 
home  with  him  from  Singapore.  **  Its  disposition  was 
gentle  but  animated  and  lively ;  and  it  delighted  in 
playing  frolics.  With  a  little  Papuan  child  on  board 
this  Siamang  became  very  intimate ;  they  might  often 
be  seen  sitting  near  the  capstan,  the  animal  with  its  long 
arm  round  her  neck,  eating  biscuit  together.  In  his 
gambols  with  the  child  he  would  roll  on  deck  with  her, 

as  if  in    mock  combat His   temper,    however, 

was  irritable,  and  on  being  disappointed,  or  confined,  he 
would  throw  himself  into  fits  of  rage,  screaming,  rolling 
about,  and  dashing  everything  aside  within  his  reach  : 
he  would  then  rise,  walk  about  in  a  hurried  manner,  and 
repeat  the  scene  as  before.  With  the  cessation  of  his  fit 
of   anger  he   did    not  abandon   his  purpose,   and    often 

*  Knight's  "  Pictorial  Museum  of  Animated  Nature,"  p.  31. 


824  THE    MENTAL    CAPACITIES    AND 

gained   his   point   by    stratagem    when    he    found   that 
violence  was  of  no  avail." 

An  instance  of  this  animal's  Intelligence  is  given  which 
is  very  interesting: — 

*' Among  various  articles  in  Mr.  Bennett's  cabin  a  piece  of  soap 
greatly  attracted  his  attention,  and  for  the  removal  of  this  soap  he 
had  been  once  or  twice  scolded.  One  morning  Mr.  Bennett  was 
writing,  the  Siamang  being  present  in  the  cabin,  when,  casting  his 
eyes  towards  the  animal,  he  observed  him  taking  the  soap.  '  I 
watched  him,'  says  the  narrator,  '  without  his  perceiving  that  I 
did  so;  he  occasionally  cast  a  furtive  glance  towards  the  place 
where  I  sat ;  I  pretended  to  write ;  he,  seeing  me  busily  engaged, 
took  up  the  soap  and  moved  away  with  it  in  his  paw.  When  he 
had  walked  half  the  length  of  the  cabin,  I  spoke  quietly,  without 
frightening  him.  The  instant  he  found  I  saw  him,  he  walked  back 
again,  and  deposited  the  soap  nearly  in  the  same  place  whence  he 
had  taken  it:  thus  betraying  both  by  his  first  and  last  actions  a 
consciousness  of  having  done  wrong." 

M.  Duvauncel  says  : — "  If  a  young  one  be  wounded,  the 
mother,  who  carries  it  or  follows  it  closely,  remains  with 
it,  utters  the  most  lamentable  cries,  and  rushes  upon  the 
enemy  with  open  mouth  ;  but  being  unfitted  for  combat 
knows  neither  how  to  deal  nor  shun  a  blow.  It  is," 
he  adds,  "  a  curious  and  interesting  spectacle,  which  a 
little  precaution  has  sometimes  enabled  me  to  witness,  to 
see  the  females  carrying  their  young  ones  to  the  water, 
and  there  wash  their  faces  in  spite  of  their  childish 
outcries — bestowing  a  degree  of  time  and  care  on  their 
cleanliness  which,  in  many  cases,  the  children  of  our 
own  species  might  envy." 

In  the  conformation  of  their  brain  the  Chimpanzee, 
the  Gorilla,  and  the  Orang  approach,  as  we  have  seen, 
most  closely  to  that  of  Man;  but  it  must  never  be  forgotten 
that  although  in  general  shape,  in  the  disposition  of  its 


Chap.  XVIII.]      POWERS    OF    HIGHER  BRUTES.  325 

Fissures,  and  in  the  arrangement  of  its  Convolutions,  as 
far  as  they  go,  there  is  this  striking  resemblance  to  the 
human  brain,  yet  in  actual  size  or  weight  the  brain  of  the 
*  man-like  '  Apes  is  widely  separated  from  that  of  Man. 
The  heaviest  brain  belonging  to  one  of  these  creatures, 
as  yet  examined,  has  been  barely  one-half  of  the  weight  of 
the  smallest  normal  human  brains,  although  the  weight 
of  the  entire  body  in  the  great  Gorilla  may  be  nearly 
double  that  of  an  ordinary  Man.  The  brains  of  these 
three  kinds  of  *  man-like  '  Apes  differ  considerably  among 
themselves ;  as  we  have  seen,  each  in  some  respects 
approaches  nearer  to  that  of  Man  than  the  others,  though 
on  the  whole  it  is  considered  that  the  brain  of  the  Orang 
is  slightly  higher  in  type  than  that  of  the  other  two. 
They  likewise  differ  from  one  another  a  good  deal  in 
disposition  and  in  general  bearing. 

Some  years  ago  a  very  interesting  baby  Chimpanzee 
was  obtained  from  the  natives  of  the  Gambia  coast. 
His  mother  had  been  shot  when  he  was  about  twelve 
months  old,  and  after  a  short  time  he  was  sent  to  London, 
and  became  famous,  young  as  he  was,  for  his  great 
intelligence  and  human-like  conduct.  Soon  after  his 
arrival  at  the  Zoological  Gardens,  this  young  Chim- 
panzee was  visited  by  a  distinguished  zoologist,  Mr. 
Broderip,  who  has  given  the  following  account  of  him 
(Cassell's  "  Nat.  Hist.,"  p.  54)  :— 

*'  I  saw  him  for  the  first  time  in  the  kitchen  belonging  to  the 
keeper's  apartments,  dressed  in  a  little  Guernsey  shirt,  or  banyan 
jacket.  He  was  sitting  child-like  in  the  lap  of  a  good  old  woman, 
to  whom  he  clung  whenever  she  made   show  of  putting  him  down 

He  had  already  become  very  fond  of  his  good  old  nurse, 

and  she  had  evidently  become  attached  to  her  nursling,  although 

they  had  only  been  acquainted  for  three  or  four  days On 

another  occasion,  and  when  he  had  become  familiar  with  me,  I 
caused,  in  the  midst  of  his  play,  a  looking-glass  to  be  brought  and 
15 


826  THE    MENTAL    CAPACITIES    AND 

held  before  him.  His  attention  was  constantly  and  strongly 
arrested :  from  the  -utmost  activity  he  became  immovably  fixed, 
steadfastly  gazing  at  the  mirror  with  eagerness,  and  something  like 
wonder  depicted  in  his  face.  He  at  length  looked  up  at  me,  then 
again  gazed  at  the  glass.  The  tips  of  my  fingers  appeared  on  one 
side  as  I  held  it;  he  put  his  hands  and  then  Lis  lips  to  them,  then 
looked  behind  the  glass,  and  finally  passed  his  hands  behini  it, 
evidently  to  feel  if  there  were  anything  substantial  there  .  .  .  A3 
I  was  making  notes  with  a  paper  and  pencil,  he  came  up  and  looked 
at  me  inquisitively,  testing  the  pencil  with  his  teeth  when  he  had 
it  given  to  him.  A  trial  was  made  of  the  little  fellow's  conrage; 
for,  when  his  attention  was  directed  elsewhere,  a  hamper  ccmtaining 
a  large  snake,  called  Python,  was  brought  in  and  placed  on  a  chair 
near  the  dresser.  The  lid  was  raised,  and  the  basket  in  which  the 
snake  was  enveloped  was  opened,  and  soon  after  Tommy  came 
gambolling  that  way.  As  he  jumped  and  danced  along  the  dresser 
towards  the  basket  he  was  all  gaiety  and  life ;  suddenly  he  seemed 
to  be  taken  aback,  stopped,  cautiously  advanced  towards  the  basket, 
peered  or  rather  craned  over  it,  and  instantly,  with  a  gesture  of 
horror  and  aversion,  and  the  cry  of  '  Hoo !  hoo ! '  recoiled  from  the 
detested  object,  jumped  back  as  far  as  he  could,  and  then  sprang  to 
his  keeper  for  protection.  Tommy  does  not  like  confinement,  and 
when  he  is  shut  up  in  his  cage,  the  violence  with  which  he  pulls  at 
and  shakes  the  door  is  very  great,  and  shows  considerable  strength  ; 
but  I  have  never  seen  him  use  this  exertion  against  any  other  part 
of  the  cage,  though  his  keeper  has  endeavoured  to  induce  him  to 
do  so,  in  order  to  see  whether  he  would  make  the  distinction.  Then 
he  went  to  a  window,  opened  it  and  looked  out.  I  was  afraid  that 
he  might  make  his  escape,  but  the  words  '  Tommy,  no !  '  pro- 
nounced  by  the  keeper  in  a  mild  but  firm  tone,  caused  him  to  shut 
the  window  and  to  come  away.  He  is,  in  truth,  a  most  docile  and 
afiectionate  animal,  and  it  is  impossible  not  to  be  taken  with  the 
expressive  gestures  .and  looks  with  which  he  courts  your  good 
opinion,  and  throws  himself  upon  you  for  j^i'otection  against 
annoyance." 

Whether  these  animals  grow  cross  and  savage  as  they 
get  old,  after  the  manner  of  Monkeys  generally,  is  not 
known,  for  no  adults  have  been  kept  in  captivity  ;  we  have, 
therefore,  also  no  means  of  forming  an   opinion  of  the 


Chap.  XYIII.]      POWERS    OF    HIGHER    BRUTES.  3*27 

degree  of  Intelligence  which  they  are  capable  of  displaying 
in  their  adult  condition.* 

We  labour  under  the  same  disadvantage  in  regard  to 
the  Gorilla,  though  Mr.  Moore,  the  Curator  of  the  Free 
Public  Museum,  Liverpool,  has  given  us  some  interest- 
iug  particulars  concerning  a  young  male,  three  feet  high, 
and  between  two  and  three  years  old,  which  was  brought 
to  that  city  by  the  German  African  Society's  Expedition.! 

"  Could  it  have  graced,"  says  this  observer,  "  our  Zoological 
Gardens,  it  would  have  been,  the  lion  of  the  day ;  for  in  addition 
to  the  great  scientific  interest  of  the  species,  the  abounding  Ufe, 
energy,  and  joyous  spirits  of  this  example  would  have  made  it 
a  universal  favourite.  Courteously  received  at  Eberle's  Alex- 
andra Hotel  by  the  members  of  the  Expedition,  I  found  the 
creature  romping  and  rolling  in  full  liberty  about  the  private 
drawing-room,  now  looking  out  of  the  window  with  all  becom- 
ing gravity  and  sedateness,  as  though  interested  but  not  discon- 
certed by  the  busy  multitude  and  novelty  without,  then  bounding 
rapidly  along  on  knuckles  and  feet  to  examine  and  poke  fun  at 

*  The  importance  of  Attention  as  one  principal  factor  in  the 
intelligence  of  animals  is  illustrated  by  the  following  interesting 
facts  communicated  to  Darwin  by  Mr.  Bartlett,  of  the  Zoological 
Gardens  : — "  A  man  who  trains  Monkeys  to  act  used  to  purchase 
common  kinds  from  the  Zoological  Society,  at  the  cost  of  five 
pounds  each,  but  he  offered  to  give  double  that  price  if  he  might 
keep  three  or  four  of  them  for  a  few  days,  in  order  to  select  one. 
When  asked  how  he  could  possibly  so  soon  learn  whether  a  par- 
ticular Monkey  would  turn  out  a  good  actor,  he  answered  that  it 
all  depended  upon  their  power  of  attention.  If,  when  he  was 
talking  and  explaining  anything  to  a  Monkey,  its  attention  was 
easily  distracted,  as  by  a  fly  on  a  wall  or  other  trifling  object,  the 
case  was  hopeless.  If  he  tried  punishment  to  make  an  inattentive 
Monkey  act,  it  turned  sulky.  On  the  other  hand,  a  Monkey  which 
carefully  attended  to  him  could  always  be  trained."  The  tendency 
to  imitation  which  Apes  and  Monkeys  often  manifest  in  a  high 
degree,  doubtless  much  facilitates  their  acquisition  of  new  motor 
accomplishments. 

t  Quoted  in  Cassell's  "  Nat.  Hist/'  vol.  i,  p.  35. 


328  THE    MENTAL    CAPACITIES    AND 

some  new  comer,  playfully  mumbling  at  his  calves,  pulling  at  hia 
beard  (a  special  delight),  clinging  to  his  arms,  examining  his  hat 
(not  at  all  to  its  improvement),  curiously  inquisitive  as  to  his 
umbrella,  and  so  on  with  visitor  after  visitor.  If  he  becomes  over- 
excited by  the  fun,  a  gentle  box  on  the  ear  would  bring  him  to  order, 
like  a  child,  only  to  be  ou  the  romps  again  immediately.  He  points 
with  the  index-finger,  claps  with  his  hands,  puts  out  his  tougue, 
feeds  on  a  mixed  diet,  decidedly  prefers  roast  meats  to  boiled,  eats 
strawberries,  as  I  saw,  with  delicate  appreciativeness,  Is  exquisitively 
clean  and  mannerly.  The  palms  of  his  hands  and  feet  are  beauti- 
fully plump,  soft,  and  black  as  jet.  He  has  been  eight  months  and 
a  half  in  the  possession  of  the  Expedition." 

This  animal  was  very  shortly  afterwards  taken  to 
Berlin,  and  a  paragraph  in  "  Nature,"  Nov.  9, 1876,  gives 
some  further  interestiiig  particulars  concerning  him,  which 
were  communicated  by  Dr.  Hermes  to  the  meeting  of  the 
*  German  Association  of  Naturalists  and  Physicians.' 

"  He  nods  and  claps  his  hands  to  visitors ;  wakes  up  like  a  man, 
and  stretches  himself.  His  keeper  must  always  be  beside  him,  and 
eat  with  him."  They  partake  of  the  same  food.  He  sleeps  for 
eight  hours.  "His  easy  life  has  increased  his  weight  in  a  few 
months  from  thirty-one  to  thirty-seven  pounds.  For  some  weeks 
he  had  inflammation  of  the  lungs,  when  his  old  friend  Dr.  Falken- 
stein  was  fetched,  who  treated  him  with  quinine  and  Ems  water, 
which  made  him  better.  When  Dr.  Hermes  left  the  Gorilla  on  the 
previous  Sunday  the  latter  showed  the  doctor  his  tongue, 
clapped  his  hands,  and  squeezed  the  hand  of  the  doctor,  as 
an  indication,  the  latter  believed,  of  his  recovery.  In  fact  the 
Gorilla  is  now  one  of  the  most  popular  inhabitants  of  the  Prussian 
capital."  In  July,  1877,  he  paid  a  visit  to  London,  and  fully  sus- 
tained the  rei)utation  he  had  already  acquired. 

Speaking  of  an  Orang  which  he  had  examined  and 
watched,  Buffon  says  : — 

**  Its  air  was  melancholy,  its  deportment  grave,  its  nature  more 
gentle  and  very  different  from  other  apes.  Unlike  the  baboon  or 
the  monkey,  whose  motions  are  violent  and  appetites  capricious, 
who  are  fond  of  mischief,  and  only  obedient  through  fear,  a  look 


Chap,  XVIIL]      POWERS    OF    HIGHER   BRUTES.  329 

Wcas  sufficient  to  keep  it  in  awe.  I  have  seen  it  give  its  hand  to  show 
the  company  to  the  door,  that  came  to  see  it,  and  it  would  walk 
gravely  with  them  as  if  one  of  the  society.  I  have  seen  it  sit  at 
table,  unfold  its  napkin,  wipe  its  lips,  make  use  of  the  spoon  and 
fork  to  carry  the  victuals  to  its  mouth,  pour  out  its  drink  into  a 
glass,  touch  glasses  when  invited,  take  a  cup  and  saucer  and  lay 
them  on  the  table,  put  in  sugar,  pour  out  its  tea,  leave  it  to  cool 
before  drinking,  and  all  this  without  any  other  instigation  than  the 
signs  or  command  of  its  master,  and  often  of  its  own  accord.  It 
was  gentle  and  inoffensive :  it  even  approached  strangers  with 
respect,  and  came  rather  to  receive  caresses  than  to  offer  injuries  : 
it  ate  of  almost  everything  that  was  offered  to  it,  but  it  preferred 
dry  and  ripe  fruit  to  all  other  aliments.  It  would  drink  wine,  but 
in  small  quantities,  and  willingly  left  it  for  milk,  or  any  other  sweet 
liquor." 

Again  in  regard  to  the  high  degree  of  Intelligence  of 
the  Orang,  we  have  the  following,  on  the  best  of  testi- 
mony, from  Leuret,  who  says*: — 

"One  of  the  Orangs,  which  recently  died  at  the  Menagerie 
of  the  Musee,  was  accustomed,  \vhen  the  dinner-hour  had  come, 
to  open  the  door  of  the  room  where  he  took  his  meals  in 
company  with  several  persons.  As  he  was  not  sufficiently  tail  to 
reach  as  far  as  the  key  of  the  door,  he  hung  on  to  a  rope,  balanced 
himself,  and  after  a  few  oscillations  very  quickly  reached  the  key. 
His  keeper,  who  was  rather  worried  by  so  much  exactitude,  one  day 
took  occasion  to  make  three  knots  in  the  rope,  which,  having  thus 
been  made  too  short,  no  longer  permitted  the  Orang-outan  to  seize 
the  key.  The  animal,  after  an  ineffectual  attempt,  recognizing  the 
nature  of  the  obstacle  which  opposed  his  desire,  climbed  up  the 
rope,  placed  himself  above  the  knots,  and  untied  all  three,  in  the 
presence  of  M.  Geoffroy  Saint- Hilaire,  who  related  the  fact  to  me. 
The  same  ape  wishing  to  open  a  door,  his  keeper  gave  him  a  bunch 
of  fifteen  keys ;  the  ape  tried  them  in  turn  till  he  had  found  the  one 
which  he  wanted.  Another  time  a  bar  of  iron  was  put  into  his 
hands,  and  he  made  use  of  it  as  a  lever." 

Unfortunately  nothing  is  said  as  to   the   age  of    this 
animal,  whose  power  of  realizing  the  nature  of  unfamiliar 
*  *  Anat.  Comp.  du  Syst.  Nerv."  t.  i.  p.  540. 


330  THE    MENTAL    CAPACITIES    AND 

conditions,  as  well  as  of  dealing  with  tliem  in  order  to  effect 
liis  own  ends,  can  only  be  described  as  highly  remarkable. 
The  following  paragraph  seems,  however,   to  refer  to 
the  emotional  manifestations  of  an  adult  Chimpanzee.* 

"  From  a  study  of  a  fine  pair  of  Chimpanzees  in  the  Philadelphia 
Zoological  Garden,  Mr.  A.  E.  Brown  has  obtained  several  interest- 
ing evidences  of  a  rather  high  degree  of  mental  power  in  this 
species.  One  of  the  pair  lately  died,  and  the  behaviour  of  the 
surviving  one  seemed  to  bear  somewhat  on  the  acquired  nature  of 
the  physical  means  by  which  our  own  strongly  excited  emotions 
find  relief,  as  well  as  on  the  origin  of  those  emotions  themselves. 
Evidences  of  a  certain  degree  of  genuine  grief  were  well  marked. 
The  animals  had  been  great  friends ;  they  never  quarrelled.  On 
the  first  cry  of  fright  from  one,  the  other  was  instantly  prepared 
to  do  battle  in  its  behalf.  It  was  early  in  a  morning  when  the 
female  died,  and  when  the  survivor  found  it  im2:>ossible  to  arouse 
her  his  grief  and  rage  were  painful  to  witness  ....  The  ordinary 
yell  of  rage  at  first  set  up  finally  changed  to  a  cry,  the  like  of  which 
he  had  never  been  heard  to  utter  before,  and  which  would  be  most 
nearly  represented  by  '  hah-ah-ah-ah-ah,'  uttered  somewhat  under 
the  breath  and  with  a  plaintive  sound  like  a  moan.  Crying  thus, 
he  would  lift  up  her  head  and  then  her  hands,  only  to  let  them  fall 
again.  After  her  body  was  removed  he  became  more  quiet;  but, 
catching  sight  of  it  on  its  being  carried  past  the  cage,  he  became 
violent  and  cried  for  the  rest  of  that  day.  The  day  following  he 
Bat  still  most  of  the  time  and  moaned  continuously ;  this  gradually 
passed  away,  the  j^laintive  cry  became  le«s  frequent,  but  when  he 
was  angry  it  would  be  heard  at  the  close  of  the  fits  just  as  the 
sobbing  of  a  child  after  a  passionate  fit  of  crying.  It  soon  became 
apparent  that  his  recollection  of  the  nature  of  the  past  association 
was  becoming  less  and  less  vivid  ;  still  it  was  noticed  that,  while 
the  two  used  to  sleep  together  in  one  blanket  on  the  fioor,  he  now 
invariably  slept  on  a  cross  beam  at  the  top  of  the  cage,  returning 
to  inherited  habit,  and  probably  showing  that  the  apprehension  of 
unseen  dangers  had  been  heighlened  by  his  sense  of  loneliness.  A 
high  degree  of  permanence  in  grief  of  this  nature  in  all  probability 
belongs  only  to  man." 

*  The  Times,  April  19,  1879. 


Chap.  XVIIL]      POWERS    OF    HIGHER    BRUTES.  331 

About  the  middle  of  the  last  century  the  celebrated  David 
Hartley  wrote*  : — '*  It  is  remarkable  that  Apes,  whose 
bodies  resemble  the  human  body  more  than  those  of  any 
other  brute  creature,  and  whose  intellects  also  approach 
nearer  to  ours — which  last  circumstance  may,  I  suppose, 
have  some  connection  with  the  first — should  likewise 
resemble  us  so  much  in  the  faculty  of  imitation.  Their 
aptness  in  handling  is  plainly  the  result  of  the  shape  and 
make  of  their  fore-legs  and  their  intellects  together,  as 
in  us.  Their  peculiar  chattering  may  perhaps  be  some 
attempt  towards  speech,  to  which  they  cannot  attain, 
partly  from  the  defect  in  the  organs  ;  partly,  and  that 
chiefly,  from  the  narrowness  of  their  memories,  appre- 
hensions, and  associations." 

If  the  anthropoid  Apes,  possessing  as  they  do  such  a 
well  defined  basis  of  Intelligence  and  Emotion,  were 
endowed  with  Articulate  Speech,  so  that  they  might 
benefit  and  mutually  instruct  one  another — even  merely 
by  oral  traditions  and  communications — how  great  a  pro- 
gress in  the  degree  and  range  of  their  Intelligence  might 
be  expected  after  a  few  hundred  generations  had  lived 
under  the  influence  of  such  conditions. 

*  "  Observations  on  Miin,"  6tli  Ed.,  1834,  p.  165. 


CHAPTEK   XTX. 

DEVELOPMENT  OF   THE  HUMAN  BRAIN   DURING  UTERINE  TilFE 

In  the  long  axis  of  the  clear  '  germinal  area'  of  the  human 
impregnated  Ovum,  there  appears  an  opaque  line  of  young 
tissue  known  as  the  '  chorda  dorsalis.' 

Above  this,  and  along  its  entire  extent,  a  shallow 
'primitive  groove'  is  found,  which  soon  becomes  bounded 
on  each  side  by  an  up-growing  lamina  of  new  embryonic 
tissue.  These  laminas  gradually  approach  one  another, 
and  ultimately  unite  over  the  before-mentioned  '  primitive 
groove'  so  as  to  form  a  distinct  tube  closed  at  each  end. 

The  internal  layer  of  this  tube  grows  in  thickness  so 
that  its  bore  becomes  gradually  narrower.  It  soon  differ- 
entiates also  into  two  distinct  textures.  The  most  internal 
of  these,  viz.,  that  immediately  surrounding  the  diminished 
central  canal,  is  composed  of  embryonic  nerve  tissue,  and 
is  destined  to  develop  into  the  Cerebro- Spinal  Axis. 

The  diameter  of  this  hollow,  rudimentary  nervous  axis 
is  not  uniform  throughout  its  whole  extent.  Even  before 
the  laminae  completely  close  over  the  *  primitive  groove,' 
the  anterior  extremity  of  the  embryo  tube  swells  into 
three  dilatations  immediately  contiguous  to  one  another ; 
and  it  is  from  the  nerve  tissue  in  these  swellings,  together 
with  that  of  certain  important  outgrowths  therefrom,  that 
the  several  parts  of  the  Human  Brain  arc  developed. 
From  the  portion  of  the  tube  behind  the  three  swellings 
the  Spinal  Cord  is  formed. 


Chap.  XIX.]        DEVELOPMENT    OF    THE    BRAIN.  333 

The  mode  of  origin  of,  as  well  as  the  early  changes 
taking  place  in,  these  three  nervous  vesicles  are  essentially 
similar,  up  to  certain  stages,  throughout  the  Vertebrata. 
From  such  a  basis,  common  to  all,  the  several  types  of 
Vertebrate  Brain  are  developed.  Our  attention  must,  how- 
ever, now  be  confined  to  tracing  in  brief  outline  the  mode 
in  which  the  brain  of  Man  gradually  develops  from  the 
simple  stages  common  to  it  and  the  Vertebrata  generally. 

In  order  that  the  reader's  attention  may  be  more  effectively 
concentrated  upon  the  subsequent  changes  undergone  by  the  three 
swellings  of  the  primary  nerve  tube,  it  may  be  well  here  to  anticipate 
a  little,  and  state  what  are  the  several  parts  of  the  Brain  which 
gradually  develop  from  them  or  their  derivatives. 

The  Posterior  Swelling  (or  Hind-brain)  becomes  divided  into  two 
regions,  of  which  the  hindermost  corresponds  with  what  subse- 
quently develops  into  the  posterior  half  of  the  Medulla,  and  here 
in  the  situation  of  the  Fourth  Ventricle  the  upper  wall  of  the  tube 
becomes  thinned  away  till  all  nervous  matter  disappears,  and  only 
a  mere  membrane  remains  ('  pia  mater ')  to  roof  over  the  space 
above  mentioned,  which  is  continuous  with  the  central  canal  of  the 
tube  behind  it.  The  anterior  region  of  this  swelling  corresponds 
with  the  anterior  half  of  the  Medulla.  From  the  back  or  sides  of  it 
there  grows  a  distinct  segment  of  the  future  brain,  viz.,  the  Cere- 
helium  (fig.  122,  c  b).  Much  later  on,  when  the  lateral  lobes  of 
the  Cerebellum  have  made  their  appearance,  this  region  of  the 
Medulla  is  crossed  below  by  the  Pons  Varolii  {jp). 

The  Middle  8ioelli7ig  (or  Mid-brain)  affords  the  matrix  from 
the  upper  part  of  which  deveiojDS  the  Optic  Lobes  or  Corpora 
Quadrigemina  (fig.  122,  q).  From  the  lower  part  are  differentiated 
prolongations  from  the  fibrous  '  columns '  of  the  Cord  and  Medulla, 
known  as  the  Cerebral  Pp.duncles  (r).  The  cavity  within  this  swell- 
ing gradually  diminishes  till  in  Man  it  persists  only  as  a  narrow 
passage  (6)  between  the  cavities  of  the  Hind  and  of  the  Fore- brain 
(the  Fourth  and  Third  Yeutricles)  {a  c).  This  passage  is  known 
as  the  'Sylvian  aqueduct.' 

The  Anterior  Swelling  (or  Fore-brain)  undergoes  remarkable 
modifications,  principally  on  account  of  certain  extraordinary  out- 
growths to  which  it  gives  rise.     From  the  sides  of  this  swelling 


334 


DEVELOPMENT    OF    THE    HUMAN    BRAIN 


are  developed  other  portions  of  the  Cerehral  Peduncles  and  also 
the  Thalami  which  rest  upon  and  grow  as  ganglionic  thickenings 
from  the  latter  structures.  Its  diminished  cavity  persists  as  the 
future   Third  Ventricle  {a).    Its  roof  becomes  gradually  thinned 


Fig.  122.— Diagrams  illustrating  the  Progressive  Changes  that  take  place  during 
the  Early  Stages  of  the  Development  of  the  Brain.     (Mivart.) 

1.  Early  condition  of  Brain  when  it  consists  of  three  hollow  vesicles  (a  b  c),  the 
cavity  of  which  is  continuous  with  the  wide  cavity  {d)  of  the  primitive  Spinal 
Cord  (»(.). 

2.  Here  the  first  vesicle  or  Fore-brain  has  developed  the  Pineal  Body  (  pi)  above, 
and  the  Pituitary  Body  (  v  t)  below.  The  wall  at  the  anterior  end  of  the  first  vesicle 
is  the  future  '  lamina  terminaUs  '  (0- 

3.  This  figure  shows  the  Cerebrum  {cr)  budding  from  the  first  vesicle,  its  anterior 
part  (o)  being  prolonged  as  the  Olfactory  Lobe  ;  the  cavity  of  the  Cerebrum  (the 
incii)icnt  'lateral  ventricle')  communicating  with  that  of  the  Olfactory  Lo])e  in 
front,  and  with  that  of  the  first  Cerebral  Vesicle  behind  (this  latter  cavity  persisting 
as  tlie  future  '  third  ventricle  ').  The  latter  communication  takes  place  through  the 
'foramen  of  Monro.'  The  walls  of  the  three  prinaitive  vesicles  are  bei-oming  of 
unequal  thickness,  and  the  cavity  (6)  of  the  middle  vesicle  is  becomiug  reduced  in 
relative  size. 

4.  The  Cerebrum  is  here  enlarged,  and  the  inequality  iu  thickness  of  the  wall  of 
the  primitive  vesicles  is  increased.  The  greater  development  of  the  Cerebellum  (<;  /<), 
the  Pons  (?))  and  the  Corpora  Quadrigemina  (7),  show  this  distinctly. 

5.  This  figure  shows  the  Cerebrum  still  more  enlarged,  and  containing  a  tri-radiate 
cavity  {I,  1,  2,  3).  The  part  destined  to  form  the  F.-rnix  (./),  which  in  No.  4  was 
above,  has  now  come  to  look  slightly  downwards,  and  prolongations  from  it  begin  to 
extend  towards  the  '  corpora  albicantia'  (<u  a),  v,  corresponds  with  the  situation  ol 
the  '  velum  interpositum.' 


CnAP.  XIX.]  DURING    UTERINE    LIFE.  835 

away  till  mere  membrane  is  left — the  'velum  interpositum ; '  at  the 
posterior  and  upper  margin  of  this  ventricle  the  Phieal  hody  {'pl) 
appears,  while  its  floor  is  prolonged  into  the  infandihuhAm,  which 
subsequently  comes  into  connection  with  the  Pituitary  hody  {p  t). 

But  at  a  very  early  period,  and  before  the  above  described  parts 
are  distinguishable,  an  outgrowth  (cr)  buds  on  each  side  from  the 
Anterior  Swelling.  These  outgrowths,  which  are  at  first  directed 
downwards  and  forwards,  are  hollow,  and  each  communicates  with 
the  Third  Ventricle  through  an  aperture  known  as  the  '  foramen 
of  Munro.'  Subsequently  these  outgrowths  undergo  an  enormous 
development  and  constitute  the  two  Cerebral  Hemispheres,  while 
their  contained  cavities  persist  as  the  '  Lateral  Ventricles,''  and  the 
Corpora  Striata  develop  within  them.  From  each  embryo  Hemi- 
sphere another  hollow  bud-like  outgrowth  develops  anteriorly,  and 
these  (o)  constitute  the  Olfactory  Lobes  and  their  peduncles. 

From  the  point  of  view  of  its  developmental  history,  therefore, 
the  entire  brain  is  capable  of  division  into  three  principal  parts  : — 
(1.)  The  Fore-brain,  consisting  of  the  Olfactory  Lobes,  the  Cere- 
bral Hemispheres,  and  the  parts  surrounding  the  Third  Yentricle; 
(2.)  the  Mid-brain,  consisting  of  the  Corpora  Qnadrigemina,  and 
the  Crura  Cerebri;  (3.)  the  Hind-Brain,  consisting  of  the  Cere- 
bellum, the  Pons  Varolii,  and  the  Medulla  oblongata.  Of  these 
principal  parts,  the  Fore-brain  admits  of  subdivision  into  three  dis- 
tinct segments,  {a)  Olfactory,  (&)  Hemispherial,  and  (c)  Thalamary; 
and  tlie  Hind-brain  into  two  segments,  (a)  Cerebellar,  (b)  Oblongate. 
The  Mid-brain  needs  no  further  subdivision.  This  classification, 
given  some  years  ago  by  Huxley,  has  the  merit  of  simplicity  when 
compared  with  other  rather  cumbrous  nomenclatures  now  in 
vogue.* 

In  fig.  122  the  beginnings  of  these  six  principal  brain  segments 
are  pretty  plainly  indicated  by  the  parts  to  which  the  following 
letters  of  reference  are  attached: — o,  cr,  a,  b,  c,  m. 

After  this  preliminary  statement,  a  more  detailed 
account  may  now  be  given  of  the  changes  undergone  by 
the  primitive  nerve  tube  with  its  cephalic  swellings,  with 
the  view  of  giving  the  reader  some  notions  as  to  the 
order  and  times  of  occurrence  of  the  several  changes. 

*  See  Gegenbauer's  "  Elements  of  Compar.  Anat."  (Engl.  Trans.) 
p.  503. 


336 


DEVELOPMENT    OF    THE    HUMAN    BRAIN 


At  a  very  early  stage  of  development,  believed  by  Tiede- 
mann  to  be  about  the  7th  week,  the  i^rimitive  nervous 
axis  or  tube  undergoes  a  series  of  bendings  (fig.  123,  a). 


Pig.  123.— Sketches  of  the  early  form  of  the  parts  of  the  Cerebro-spinal  Axis  in 
the  Human  Embryo.     (Sharpc-y,  after  Tiedemann.) 

A,  at  the  seventh  week,  hitcral  view ;  1,  spinal  cord  ;  2,  medulla  oblongata ; 
8,  cerebellum  ;  4,  mesencephalon  ;  5,  6,  7,  cerebrum. 

B,  at  the  ninth  week,  posterior  view.  1,  medulla  oblongata ;  2,  cerebellum ; 
8,  mesciijccphalon  ;  4,  5,  thalami  optici  and  cerebral  hemispheres. 

C  and  U,  lateral  and  posterior  views  of  the  brain  of  the  human  embryo  as  it 
appears  at  the  twelfth  weeki.f  intra-uterine  life,  a,  cerebrum;  b,  corpora  qiiadri- 
gemina  ;  c,  cerebellum  ;  d,  medulla  oblongata  :  the  thalami  are  now  covered  by  the 
enlarged  hemispheres, 

E,  posterior  view  of  the  same  brain,  dissected  to  show  the  deeper  parts.  1,  me- 
dulla oblongata ;  2,  cerebellum ;  3,  corpora  quadrigemina ;  4,  thalami  optici ;  5,  tbo 
hemisphere  turned  aside;  6,  the  corpus  striatum  embedded  in  the  hcmispheie  ; 
7,  the  commencement  of  the  corpus  callosum. 

F,  the  inner  side  of  the  right  half  of  the  same  brain  fcparatcd  by  a  vertical 
median  section,  showing  the  central  or  ventricular  cavity.  1,  2,  the  spinal  cord 
and  medulla  oljlongata,  still  hollow  ;  3,  l)eiKl  at  which  the  pons  Varolii  is  formed  ; 
4,  cerebellum  ;  5,  lamina  (superior  cerebellar  i)eduncles)4)assing  up  to  the  corpora 
quadrigemina  ;  (i,  crura  cerebri ;  7,  cori)ora  qviadrigemina,  still  hollow  ;  8,  third 
ventricle  ;  »,  infundibuliuu  ;  10,  thalamus,  now  solid  ;  11.  optic  nerve;  12,  aperture 
leading  into  the  lateral  ventricle  ;  13,  commencing  corpus  callosum. 

The  *  posterior  swelling  '  becomes  bent  upon  itself  so 
that  its  two  regions  (2,  3)  are  nearly  at  a  right  angle  ; 
while  thence  onwards  the  parts  form  a  curve  (4,  5,  6),  which 
is  directed  forwards  and  downwards. 


Chap.  XIX.]  DURING    UTERINE    LIFE.  337 

This  bent  tube  gradually  undergoes  various  modifica- 
tions, due  to  the  progressive  thinning  away  of  its  walls 
in  certain  places,  and  to  local  thickenings  (owing  to  the 
growth  and  development  of  new  nerve  matter)  in  other 
parts.  These  latter  regions  of  increased  thickness  corre- 
spond with  future  ganglionic  centres,  which  gradually,  in 
the  regions  already  indicated,  develop  into  the  Cerebellum, 
Pons  Varolii,  Corpora  Quadri- 
gemina,  Crura  Cerebri,  Thalami, 
and  Cerebral  Hemispheres  with 
their  enclosed  Corpora  Striata  and 

*  various  commissures.' 

From  the   7- 9  th  weeks,    the 

*  middle  swelling  '  or  vesicle  (Me- 
sencephalon), representing  the  fu-     fig.  124.— vertical  section  of 

.  /->,  /-^        T    •  •  •       J 1        the  Brain  of  a  Human  Embryo 

ture   Corpora  Qaadrigemma,   is    the    of    Fourteen    weeks,   magnified 
most     prominent     segment      of    the   thi-ee  diameters.   (Sharpey,  after 

brain.     The    Cerebellum   even    at  sphere ;  c  c,  corpus  caiiosum  be, 
the  latter  date  is  represented  only  gtr^r— ^^it" 

by  a  thin   lamella    stretching  across   third  ventricle  and  the   'plneal 
. T       T        1         p    i  1  1        /.    ,  1        body ' :  th,  thalamus  opticus ;  3, 

the  back    of   the    upper    part    of   the   third     ventricle;     I,     olfactory 
Medulla,  while  the    future  Cerebral   ^"l^^  eg.  corpora  quadrlgemlna; 
.  .  11*^'''    crura    cerebri,     and    above 

Hemispheres  exist  as  mere  oblong  them  the  'aqueduct  of  syMus- 
ampulte  (fig.  122,  3)  projecting  ^::^^;^-::T^,^ 
downward  and  forwards  from  the  pv,  poi.s  varoiu;  m,  meduiia 
original  '  anterior  swelling.'  From  ""'""S^"^^^- 
the  under  part  of  this  same  swelling  (Thalamencephalon), 
projects  the  '  infundibulum,'  which  either  at  this  time 
or  a  little  later  becomes  connected  with  the  Pituitary 
Body — a  structure  whose  real  nature  and  origin  are  still 
involved  in  much  obscurity.  From  about  the  eighth 
week  also  the  Thalamencephalon  is  so  thinned  away  above 
(fig.  122,  v)  that  the  'third  ventricle'  becomes  covered 
only   by  membrane — the   'velum  interpositum.'     At  the 


338 


DLVELOPMENT    OF    THE    HUMAN    BRAIN 


upper  and  posterior  margin  of  this  ventricle  the  '  Pineal 
body'  soon  appears,  and  also  its  *  peduncles  '  which  extend 
forwards  on  each  side. 

By  the  12th  week  of  intrauterine 
life,  the  configuration  of  the  Brain  has 
undergone  a  very  marked  change ;  first 
by  reason  of  the  increased  size  of  the 
Cerebellum,  (fig.  123,  C,  c)  which  is  now 
thicker  and  marked  by  a  median  longi- 
tudinal furrow,  though  otherwise  smooth 
on  its  surface;  and,  secondly,  by  the  still 
more  striking  development  of  the  Cere- 
bral Hemispheres  (C,  a),  which  have 
already  grown  so  much  backwards  as  com- 
pletely to  overlap  the  '  third  ventricle ' 
(fig.  123,  F,  8).  On  the  under  surface  of 
each  Hemisphere  an  Olfactory  Lobe  is 
now  very  distinct,  as  a  hollow  bud-like 
outgrowth,  the  cavity  of  which  is  con- 
tinuous with  that  of  the  Hemisphere 
from  which  it  projects. 

The    '  lateral    ventricles '    themselves 

Fi<;.    12.0.— Br;iin   and  ,.  ..■,      .■,  •, 

SpiiMi  Cord. .fa  Foetus  of  are,  morcovcr,  continuous  with  the  cavity 
Four  Months,  seen  from  ^f  ^j^g  Thalameucephalon,  or  '  third  ven- 

behiud.    (Sliarpey,  after  .  i  •  n  /? 

Koiiikcr.)  /,,  Hemi- tricle,'  byau  opening  on  each  side  ot 
spheres  of  the  Cerebrum;.       ^utorior   extremity,    kuown    bv   the 

VI,     coipora     quadnge-      "^     w^xi^v^     v-.  j, 

muia;   c,   cerebeUum ;  name  of  the  '  foramcii  of  Muiiro.'    Near 

tu  o,  medulla  oblongata,     ,   .  •  ,  i  i    i         •         a 

the  fourth  ventrieie  be-  tlus  opeuiug  a  trausvcrsc  band  begins  to 
ing  overlapped  by  the  appear     (abovo     and    in     front),     which 

CereljcUum  ;  .<;  x,  the  cer-     ^  ^  ^  ^  •       i  j      • 

vicai  and  lumbar  swell-  conuccts  tlic  two  hemispheres  and  is 
ings  of  the  spinal  eord.  ^^^^^^^,^1^^  ^^  corrcspoiid  with  the  Com- 
mencement of  the  great  transverse  commissure,  the  Corpus 
Callosum,  and  perhaps  also  with  the  Anterior  Commis- 
sure.    The  walls  of  the  Cerebral  Hemispheres  are  very 


Chap.  XIX.]  DURING    UTERINE    LIFE.  339 

tliin  and  bag-like  at  this  stage,  so  that  each  encloses  a 
very  large  'lateral  ventricle,'  within  which  a  rudimentary 
Corpus  Striatum  is  to  be  seen,  in  the  form  of  a  thick- 
ening of  its  under  and  outer  wall.  Thus  it  is  that  these 
bodies  come  to  occupy  their  well-known  position  anterior 
to  and  a  little  outside  the  Thalami. 

During  this  same  period  the  '  middle  swelling '  or 
Mesencephalon  has  not  grown  at  all  proportionately,  so 
that  it  now  has  a  much  smaller  relative  size  (fig.  124,  c  q). 
It  is,  however,  marked 
by  the  appearance  of  a 
slight  longitudinal  fur- 
row, and  its  hinder  bor- 
der touches  the  Cere- 
bell  nm  (c').  Its  upper 
walls  are  comparatively 
thin,  forming  the  roof  of 
a   proportionately  large 

cavity,   situated  between       Fig.  12G.  -Brain  of  Human  Fcetns,  of   Fourth 

'  J  „  ,  Month,  magnified,  about  two  diameters.    (Owen.) 

the  third  and  lOUrtn  Ven-  side  view,  wltli  cerebrum  (P)  tilted  upwards  and 

tricleS,  though  the  cavity  forwards   so  as  to  uncover  the  corpora  qxiadrige- 

'  *-•      ^  *^    mma  (o  o),  and  the  bilobed  Cerebellum  (c  c). 

subsequently  diminishes 

so  as  to  form  a. mere  passage  between  these  ventricles. 

The  relatively  large  Medulla  still  preserves  its  primitive 
bend.  Its  upper  half  is  bridged  over  by  the  Cerebellum, 
while  at  the  back  of  its  lower  half  is  the  widely  open 
*  fourth  ventricle,'  the  lower  part  of  which  is  continuous 
with  the  central  canal  of  the  remaining  portion  of  the 
primitive  tube  now  developing  into  the  Spinal  Cord. 

By  the  end  of  the  4th  month  the  principal  addi- 
tional changes  which  have  been  noted  are  these.  The 
Cerebral  Hemispheres  become  still  larger  and  tend  more 
and  more  to  eclipse  other  parts.  They  already  stretch 
back    over  the    future   Corpora  Quadrigemina  (fig.   126). 


340 


DEVELOPMENT    OF    THE    HUMAN    ERAlN 


A  rudimentary  '  fissure  of  Sylvius  '  is  to  be  seen  on  the 
outer  surface  of  each,  and  from  this  wide  and  deep  sulcus 
a  number  of  shallow  fissures  have  been  described  by 
Gratiolet  and  others  (corresponding  with  internal  promi- 
nences on  the  walls  of  the  lateral  ventricles).  These 
appearances  are  believed  by  some  to  be  ai-tificial ;  but 
whether  artificial  or  natural,  all  are  agreed  that  they  dis- 
appear after  a  time,  as  the  walls  of  the  '  lateral  ventricles ' 
become  thicker.  Then  it  is  that  the  permanent  *  fissures' 
and  *  convolutions'  begin  to  be  developed  on  the  external 
surface  of  the  Cerebral  Hemispheres. 

At  this  period,  too,  the  Corpora  Striata  are  distinctly 


Fig.  127.— Brain  of   Turtle  [Chelnne),   side  view,  for  comparison  with  last  figure. 
(Owen.)    C,  Cerebellum  ;  O,  optic  lobes  ;  P,  Cerebrum  ;  l\,  olfactory  lobes. 

larger,  and  not  far  from  their  anterior  extremities  a  short 
and  nearly  vertical  Corpus  Callosum  is  recognizable  (not 
very  difi'erent  from  that  which  exists  in  Marsupials). 
The  Anterior  Commissure  is  slender  but  distinct.  The 
Middle  or  Soft  Commissure  exists  in  the  form  of  a 
large  rounded  projection  from  the  inner  face  of  each 
Thalamus,  though  the  two  prominences  have  not  yet  come 
into  contact  with  one  another,  so  as  to  form  an  actual 
Commissure. 

The  cavity  within  the  Optic  Lobes  is  even  larger  than 
it  was  at  an  earlier  date.  The  lateral  lobes  of  the  Cere- 
bellum have  developed  notably,  whilst  they  are  separated 
from  one  another  (fig.  126,  c)  by  a  median  depression— 


Chap.  XIX.] 


DURING    UTERINE    LIFE. 


341 


indicative  of  the  almost  complete  absence  at  this  j)eriocl  of 
the  Median  Lobe. 

On  examining  the  base  of  the  brain,  the  Medulla  is 
found  to  be  large.  The  '  anterior  pyramids/  and  the  rudi- 
ments of  the  '  olivary  bodies '  outside  them,  are  quite 
distinctly  recognizable.  A  thin  band,  marked  by  a  median 
furrow,  is  to  be  seen  stretching  across  between  the  lateral 
lobes  of  the  Cerebellum.  This  is  the  first  trace  of  the 
'  pons  Varolii.'  In  front  of  it  are  the  Cerebral  Peduncles  ; 
between  these  latter  are  the  '  corpus  albicans'  and  the 
'  tuber  cinereum,'  and  in 
front  of  this  last  lies 
the  *  commissure  '  of  the 
Optic  Nerves.  All  the 
other  cerebral  nerves  are 
distinctly  recognizable, 
though  they  are  ex- 
tremely slender  at  this 
period. 

After     this      epoch    the      Fig.    128. -The   outer    surface   of  the   Foetal 
T         -  ,       f,  .-,        1        •      Brain  at  Six  Months.  (Sharpey,  after  R.  Wagner.) 

aeveiOpment  01  the   bram  This  and  the  next  figures  are  intended  to  show 
S'OeS      on         according"      to  *^®  commencement  of    the    formation    of    the 
.  '       ,  ^  principal  fissures.     F,  Frontal  lobe ;  P,  parietal  ; 

Gratiolet,  with  most  SUr-  O,  occipital ;  T,  temporal  ;  a  a  a,  slight  appear- 
^•„'  ■  1-j  -D      4-1,  «  f'nce  of  the  several  frontal  convolutions  ;  ss,  the 

prismg  rapidity.    By  the  ^^,^^^  ^3,,,,, .  ,,^  ,,^  ^^.^^.^^  ^j^j^.^^'^  ^;  ,j^^ 

end.  of  the    5tll  month,    ^^ttorn  of  it,  C,  the  central  lobe  or  island  of  Reil ; 
.,  1        f.     1         /-i  '■'  fissure  of  Rolando ;  p,  the  external  perpen- 

the  groAvth  of  the  Cere-  dicuiar  fissure. 
bral     Hemispheres    has 

been  so  great  that  they  completely  cover  not  only  the 
Corpora  Quadrigemina  but  also  the  now  larger  Cerebellum. 
The  '  fissure  of  Sylvius '  is  wide  and  open  (fig.  128),  so  as 
to  leave  uncovered  the  central  lobe  or  '  island  of  Eeil.' 
The  beginning  of  the  '  fissure  of  Rolando  '  is,  at  this  period, 
sometimes  recognizable, while  the  rudiments  of  convolutions 
are  to  be  traced  upon  the  frontal  lobes  and  other  parts.     The 


342  DEVELOPMENT    OF    THE    HUMAN    BHaIN 

walls  of  the  Hemispheres  and  also  of  the  Optic  Lobes 
have  acquired  a  much  greater  thickness  and  the  principal 

*  commissures  '  have  in  great  part  assumed  their  typical 
condition.  This  is  the  case  more  especially  with  the 
Corpus    Cailosum    and   the    Fornix,    between   which  the 

*  fifth  ventricle '  has  begun  to  appear.  The  two  halves 
of  the  Middle  Commissure  have  also  grown  together. 

During  the  same  period  the 
Cerebellum  has  undergone 
important  changes.  From  the 
end  of  the  fourth  month  the 
development  of  its  '  lateral 
lobes '  takes  place  at  a  slower 
rate,  and  the  previously  absent 
'  median  lobe  '  not  only  begins 
to  appear  but  also  becomes 
marked  on  the  surface  by 
three  or  four  transverse  folds. 
The  '  lateral  lobes '  are  still 
perfectly  smooth — though  by 

Fig    129.-The  upper  surface  of  the  ^j         OUd     of   the  sixth    mOUth 
Foetal  Braui  at  Six  Months,    (febarpey, 

after  R.  Wagner.)     Letters  of  refereuce  they     alsO    liaVO  acquircd    UU- 

as  in  last  figure.                                                                      .  ^ 

merous  transverse  tissures. 
The  pons  Varolii,  as  already  intimated,  undergoes  a 
development  correlative  with  that  of  the  lateral  lobes  of 
the  Cerebellum. 

In  the  remaining  important  section  of  intrauterine  life, 
from  the  6th  to  the  end  of  the  9th  month,  the  develop- 
mental changes  in  the  Cerebrum  are  much  more  marked 
than  they  are  in  the  Cerebellum.  The  walls  of  the  Cerebral 
Hemispheres  become  thicker,  and  there  is  a  proportionate 
diminution  in  the  capacity  of  the  '  lateral  ventricles,'  the 
three  '  horns '  of  which  now  become  quite  distinct.  The 
Corpus  Cailosum  assumes   a   more  horizontal  direction, 


Chap.  XIX.] 


DURING    UTERINE    LIFE. 


343 


whilst  it  increases  both  in  thickness  and  in  length.  It 
reaches  back  as  far  as  the  Optic  Lobes,  which  are  now 
marked  by  a  transverse  furrow,  and  thus  appear  as  true 
*  Corpora  Quadrigemina.'  The  Occipital  Lobes  of  the 
brain  become  more  developed.  The  general  outline  of  the 
Hemispheres 
seen  from  above 
is  that  of  an 
elongated  oval. 
During  the 
sixth  month  a 
surprising  devel- 
opment of  the 
Fissures  and 
Convolutions 
takes  place,  so 
that  early  in  the 

Fig.  130.— View  of  the  inner  surfuce  of  the  Right  Half  of 
seventh       month  the  Foetal  Brain  of  about  Six  Months.     (Sharpey,  after  Rei- 

all  the   pidncipar^"|>/',/7^^^V"i^^L^'  parietal  ;0,  occipital  :  Ttem- 

■•■  J-        poral;  I,  olfactory  bulb;  II,  right  optic  neive;  /^j,  calloso- 

of  them  are  dis-  marginal  fissure;  p,  perpendicular  fissure;  ?/,  internal  per- 

.  1     ,  ^  -1  1       pendicular  fisstire  ;  h,  calcarine  fissure  ;  gg,  gyrus  fornicatus ; 

tinCtlJtraCeaOie.  ^  ^^  corpus  callosum;  s,  septum  lucidum;  /,  placed  between 

Those      which  ^^^  middle  commissure  and  the  foramen  of  Monro ;  v,  in  the 

vipper  part  of  the  third  ventricle,  immediately  below  the 

manliest      them-  velum  Interposltum  and  fornix  ;  v',  in  ihe  back  part  of  the 

Qpl  vp  «      fi  r  cjf      nn  *^^^^^  ventricle  below  the  pineal  gland,  and  before  the  entrance 

beiveh      lllbl      on  ^^  ^^^^  'aqueduct  of  Sylvius;'  v",  in  the  lower  part  of  the 

the  external  SUr-  third  ventricle  above  the  Infundibulum;  r,  processus  pinealis 

i»  2.^        c  It       passing  backwards  from  the  tela  choroidea;  2J 1-,  pons  Varolii  ; 

lace  are  the      tlS-  ce,  cerebellum. 

sure  of  Sylvius' 

and  the  '  fissure  of  Eolando.'  The  latter  is  scarcely  distinct 
till  the  end  of  the  sixth  month,  but  rather  before  this 
period,  according  to  Ecker,  two  other  Fissures  appear  on 
the  inner  aspect  of  the  Hemispheres,  viz.,  the  'internal 
perpendicular '  (fig.  130,  P^)  marking  the  anterior  boundary 
of  the  Occipital  Lobe  and  the  '  calcarine  fissure  '  which  it 
meets  below.     The  latter  is  generally  regarded  as  a  pos- 


344  DEVELOPMENT    OF    THE    HUMAN    BRAIN 

fcerior  extension  of  the  '  fissure  of  the  Hippocampus,'  which 
appears  about  the  same  time,  and  is  a  marking  constantly 
present,  even  in  lower  Vertebrates,  on  the  inner  side  of 
the  brain.  Gratiolet  indeed  believes  that  this  latter  fissure 
is  the  first  to  appear  on  the  inner  side  of  the  hemisphere. 
Eather  later  the  *  parallel  fissure '  of  the  Temporal  Lobe 
becomes  distinguishable,  and,  as  above  stated,  by  the 
beginning  of  the  seventh  month,  the  other  principal  fis- 
sures of  the  brain  have  made  their  appearance. 

Probably  Ecker  is  correct  in  his  view  that  the  precise 
time  at  which  the  principal '  fissures '  appear,  as  well  as  their 
exact  order  of  appearance,  is  subject  to  some  variation  in 
different  individuals.  Both  he  and  Huxley  consider  there 
is  no  evidence  to  show  that  the  fissures  of  the  brain  of  a 
Chimpanzee  or  of  an  Orang  do  not  appear  in  essentially 
the  same  order  as  those  of  the  Human  Infant,  notwith- 
standing the  opinion  expressed  by  Gratiolet  to  the  effect 
that  there  are  certain  slight  differences. 

At  the  time  of  birth  the  development  of  the  convolutions 
is  so  complete  in  the  Human  Infant  that  they  differ  from 
those  of  the  adult,  only  by  presenting  a  little  less  of  com- 
plication in  regard  to  minor  details. 

During  the  attainment  of  this  degree  of  couA^olutional 
complexity,  however,  some  important  changes  have  been 
taking  place  in  the  relative  development  of  the  different 
*  Lobes  '  of  the  brain.  At  the  seventh  month  the  Parietal 
Lobe  is  notably  small,*  and  aj)parently  as  a  consequence 
of  this  the  *  fissure  of  Kolando  '  is  bent  nearly  at  right 
angles,  just  as  it  is  in  the  brains  of  the  adult  Orang  and 
to  a  less  extent  in  that  of  the  Chimpanzee.  At  this  same 
period  the  Frontal  Lobe  is  large,  and  so  also  is  the 
Temporal  Lobe,  though  its  convolutions  are  still  very 
imperfectly  marked  out.      The  length   of  the   Temporal 

*  See  Gratiolet's  "Anat.  Comp  du  Syst.  Nerv.,"  PI.  xxxi,  fig.  1. 


Chap.  XIX.]  DURING    UTERINE    LIFE.  345 

Lobe  and  the  extent  of  the  posterior  prolongation  of  the 
*  fissure  of  Sylvius '  are  also  notable  features  of  the  foetal 
brain.  We  have  already  had  to  refer  to  these  charac- 
teristics in  the  brains  of  many  of  the  Quadrumana,  and 
we  shall  have  occasion  again  to  speak  of  the  same  pecu- 
liarities as  existing  among  fully  developed  Human  Brains 
of  a  low  type. 

At  the  period  of  birth,  with  the  fuller  development  of 
the  Parietal  Lobe,  the  fissure  of  Rolando  is  much  less 
bent.  The  outline  of  the  Brain  seen  from  above  is  still 
that  of  an  elongated  oval,  though  it  is  one  which  is  dis- 
tinctly fuller  in  the  frontal  as  well  as  in  the  parietal  region 
than  that  of  the  seventh  month  foetus  represented  by 
Gratiolet — the  outline  of  which  agrees  almost  exactly  with 
the  outline  of  the  brain  of  the  adult  Bushwoman  given  by 
Marshall  (fig.  135). 

According  to  S.  Van  der  Kolk  and  Yrolik  it  appears 
that  in  their  relative  proportions  the  lobes  of  the  Brain  in 
a  new-born  Child,  hold  just  the  mean  between  those  of  a 
Chimpanzee  and  of  an  adult  Man.  In  the  adult  Orang, 
however,  the  same  proportion  obtains  between  its  different 
lobes  and  those  of  the  new-born  Child — so  that  in  this 
respect,  as  in  several  others,  the  brain  of  the  Orang  seems 
rather  more  highly  evolved  than  that  of  the  Chimpanzee. 

The  Cerebellum  in  the  new-born  Child  is  comparatively 
small.  Its  proportionate  weight  compared  with  that  of 
the  Cerebrum  at  the  same  period,  is  lower  than  in  either 
of  the  great  anthropoid  Apes.  This,  however,  is  due  not 
to  any  diminution  in  the  development  of  the  Cerebellum, 
but  rather  to  the  fact  that  in  Man  the  amount  of  increase 
in  the  size  of  the  Cerebrum  is  much  more  considerable 
than  in  that  of  the  Cerebellum,  and  because  this  greater 
increase  is  already,  at  the  time  of  birth,  more  manifest  in 
the  Cerebrum  than  in  the   Cerebellum.     This  fact   waa 


346  DEVELOPMENT    OF    THE    HUMAN    BRAIN. 

also  established  by  the  above-mentioned  Dutch  Ana- 
tomists, since  they  found  that  the  weight  of  the  Cere- 
brum in  the  new-born  infant  was  to  its  weight  in  the 
adult  as  96 :  157  ;  while  the  weight  of  the  Cerebellum  in 
the  new-born  infant  was  to  its  weight  in  the  adult  only 
as  '22 :  50. 

The  actual  ratio  of  the  weight  of  the  Cerebellum  to 
that  of  the  Cerebrum  in  the  new-born  infant  was  found 
by  Chaussier  to  vary  from  1 :  13  to  1 :  26 ;  and  by  Cruvel- 
hier  it  was  ascertained  to  be  1 :  20.  On  the  other  hand, 
according  to  Sharpey,  the  ratio  of  the  weight  of  the  Cere- 
bellum to  that  of  the  Cerebrum  in  the  adult  male  is  1 :  8y, 
and  in  the  adult  female,  1 :  8|-. 

From  these  figures  it  maybe  seen  how  very  considerably 
the  development  of  the  Cerebellum  lags  behind  that  of  the 
Cerebrum  in  the  Human  Infant  at  the  time  of  birth. 

In  regfird  to  the  microscopical  characters  of  the  foetal 
brain  ov.e  brief  but  important  statement  deserves  to  be 
recorded. 

According  to  Lockhart  Clarke^: — **  In  the  early  foetal 
brain  of  Mammalia  and  Man  the  structure  [of  the  cere- 
bral convolutions]  consists  of  one  uninterrupted  nucleated 
network.  As  development  advances  separate  layers  may 
be  distinguished."  But  even  in  these  layers  there  are 
only  to  be  recognized  "  roundish  nuclei  connected  by  a 
network  of  fibres,"  or,  in  other  jiarts,  groups  of  more 
elongated  nuclei,  ia  place  of  the  distinct  but  differently 
shaped  Nerve  Cells  with  inter-connecting  processes,  which, 
in  a  later  chapter,  will  be  described  as  the  prevailing  and 
characteristic  constituents  of  the  Cerebral  Convolutions  in 
their  developed  condition. 

*  "Notes  of  Ecsearches  on  the  Intimate  Structure  of  the 
Eraiu,"  Proceed,  of  lloijal  Suciclij,  18(J-'5,  p.  721. 


CHAPTER  XX. 

THE    SIZE   AND   WEIGHT    OP   THE    HUMA"fT   BEAL?. 

The  size  and  weight  of  the  Human  Brain  are  capable  of 
being  estimated  in  two  ways,  the  one  of  which  may  be 
termed  'direct,'  and  the  other  'indirect.' 

We  may,  of  course,  measure  and  weigh  the  organ  when 
it  is  accessible,  and  an  enormous  amount  of  labour  has 
been  expended  in  this  direction — especially  by  British 
obserYers — upon  individuals  of  different  ages,  sexes,  and 
conditions. 

But  when  of  the  representatives  of  ancient  peoples,  of 
foreign  nations,  or  of  savage  tribes,  all  that  the  anatomist 
possesses  are  mere  brain-cases  or  skulls,  he  must,  if  he 
would  acquire  definite  notions  as  to  the  size  and  weight 
of  the  organs  which  they  previously  contained,  adopt  some 
uniform  and  carefally  worked-out  method  for  ascertain- 
ing their  exact  cubical  capacity.  From  the  figures  for 
*  cranial  capacity '  thus  ascertained,  the  probable  corre- 
sponding Brain-weight  will,  when  certain  other  data  are 
known,  be  dedncible  with  a  fair  amount  of  exactness. 

This  latter  '  indirect '  method  of  procedure  is  warrant- 
able and  capable  of  giving  trustworthy  results,  because  in 
health  the  human  brain  invariably  fills  the  skull  to  which 
it  belongs,  except  for  the  intervention  of  some  thin  mem- 
branous envelopes  with  vessels  and  blood-spaces — for  which 
definite  allowances  may  ultimately  be  made.     Much  work, 


348 


THE    SIZE    AND    WEIGHT 


however,  still  remains  to  be  done  before  the  amount  of  these 
allowances  or  their  range  of  variation  for  persons  of  different 
ages,  sexes,  and  races  can  be  accurately  determined ;  and 
the  same  may  be  said  in  reference  to  differences  in  the  size 
of  the  'lateral  ventricles,'  since  either  excess  or  defect  of 
the  usual  space  thus  appropriated  may  also  occasionally 
intervene  as  a  disturbing  condition,  tending  to  vitiate  an 
'  indirect '  estimation  of  Brain-weight.  Though  it  is 
true,  therefore,  that  certain  relations  ought  always  to 
obtain   between    '  cranial   capacities '   and  Brain-weights, 

these  cannot  be  said  to 
have  been  yet  deter- 
mined except  in  a  mere 
preliminary  and  tenta- 
tive manner.  According 
to  the  general  rule  laid 
down  by  Dr.  Barnard 
Davis  a  deduction  of 
about  15  per  cent,  from 
the  capacity  of  the  Cra- 

FiG  131.— One  side  of  the  Skull  removed,  sliow-  nium  givCS  tllC  'capacity' 
ing  the  Dura  Mater  with  its  vessels  enveloping      «    ,  i         i-j       •  ^    t         ^ 

the  Brain.  (After  Hirschfeld  and  Leveille.)  «,  of  tllO  BraiU,  aud  trOUl 
Commencement  of  the  gre it  longitudinal  Venous  -j-lj^jg  ^^^  WCi^ht  maV  be 
Sinus,  whi.  h  is  continued  backward  towards  6.  i       1    x*  * 

Close  to  this  is  situated  the  meeting-point  of  dcduCCd  by  CalCUlatlOll. 
several  Venous  Sinuses.  g^^j^      ^^^^     'indirect' 

and  the  'direct'  methods  are  of  great  utihty,  and  either 
may  be  had  recourse  to  by  the  experienced  investigator 
according  as  Skulls  or  Brains  present  themselves  for 
examination.  Each  method  offers  certain  advantages,  but 
on  the  whole  it  may  be  said  that  if  Brains  were  always 
accessible,  we  should  probably  hear  less  on  the  subject  of 
'cranial   capacities.'     The    'indirect'  method  seems  well 

*  Sec  "  On  the  Weight  of  the  Brain  in  the  Different  Races  of 
IMaii."  Plulos.  Trans.,  18«j8,  pp.  506  and  526. 


Chap.  XX.] 


OF   THE    HUMAN    BRAIN. 


349 


calculated  to  afford  race-averages,  or  prevailing-weights, 
where  a  sufficient  number  of  skulls  are  carefully  measured 
by  a  method  likely  to  give  uniform  and  correct  results. 

It  must  never  be  forgotten,  however,  that  the  size  of 
the  Skull,  and  with  it  the  weight  of  the  Brain,  varies 
within  certain  limits  according  to  the  stature  of  the 
individual,  in  such  a  way  that  increments  of  increasing 
stature  are  accompanied  by  increments  of  increased  Brain- 
weight,  though  the  extent  of  the  latter  increments  goes 
on  diminishing  as  the  stature  increases.  This  statement 
rests  on  the  authority  of  Marshall,*  who  has  also  calculated 
from  the  colossal  tables 
(together  with  private 
notes)  supplied  by  Boyd, 
that  for  English  people, 
with  a  mean  range  in 
stature  of  7  inches  for 
males,  the  correspond- 
ing variation  in  Brain- 
weight  is  2-75  oz.,  and 
that  for  females,  with  a 
mean  range  in  stature 
of  6  inches,  the  varia- 
tion is  only  1*25  oz.  In  ^^^-  132.— Human  Cerebrum  and  Cerebellum, 
,  ,        .        showing  the  relative  size  of  these  parts   of  the 

comparing      the      brain-  Brain.    (After  nirschfeld  and  LeveiUe.) 

weights  of   individuals 

of  different  stature,  therefore,  with  the  view  of  tracing  the 
influence  of  other  conditions  over  the  weight  of  the  organ, 
it  must  always  be  borne  in  mind  that  difference  in  stature 
itself  is  a  potent  cause  of  difference  in  brain -weight  which 
ought  to  be  allowed  for  in  the  first  instance. 

It  may  be  well  to  state  here,   in  general  terms,  that 
rather  less   than  -^th  of    a  total  Brain -weight  will,   for 

*  "Proceed,  of  Eoy.  Soc,"  1875,  vol.  xxiii.  p.  564 
16 


350  THE    SIZE    AND    WEIGHT 

males,  be  the  proportion  of  such  total  corresponding  wdth 
the  weight  of  the  Cerebellum.  For  females,  however,  the 
relative  weight  of  the  Cerebellum  is  rather  greater  (1:8-^), 
on  account  of  the  existence  in  them  of  a  greater  propor- 
tionate diminution  in  the  size  of  the  Cerebrum. 

Cranial  Capacities. 

The  average  *  cranial  capacity  '  for  any  race  can  only 
be  ascertained  by  the  examination  of  a  large  series  of 
corresponding  skulls,  assorted  according  to  Sex.  The 
importance  of  the  latter  point  is  great,  because,  as  Flower 
points  ont,  difference  in  Sex,  in  its  influence  over  capacity 
of  skull,  is  often  decidedly  greater  than  difference  of 
Place. 

The  methods  of  estimating  the  *  cranial  capacity' 
have  varied  so  much  at  different  times,  and  as  adopted 
by  different  investigators,  as  to  make  it  often  both 
difBcult  and  unsafe  to  compare  their  results  with  one 
another. 

It  is  most  important  that  an  international  method 
Bhould  be  agreed  upon,  and  universally  adopted  by  workers 
in  different  countries.  We  may  then,  after  a  time,  get 
results  strictly  comparable  with  one  another.* 

Vogt  f  gives  a  table  of  cranial  capacities  by  different 
observers,  the  most  interesting  items  of  which  have  been 
derived  from  the  researches  of  Broca  upon  large  numbers 
of  skulls  obtained  from  certain  Parisian  churchyards,  the 
remains  of  which  for  different  reasons  had  to  be  disturbed. 
He  says : — 

*  See  Flower  in  "Brit.  Met!.  Journ.,"  April  12,1870,  p.  540 
B.lso  a  paper  by  the  same  autlior  on    "  Methods  and  Eesults  of 
Measmement  of  Capacity  of  Crania,"  in  llcp.  of  Brit.  Ai>^oc.  for 
1878 

t  "  Lectures  on  Man  "  (Authn^p.  Soc),  p.  88. 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  351 

"  Broca  availed  himself  of  the  rare  opportunity  of  examining 
a  number  of  skulls  which  were  found  in  Paris,  on  laying  the 
foundation  of  the  new  Tribunal  de  Commerce,  in  a  vault,  at  a 
depth  of  three  metres,  at  a  spot  which  was  already  covered  with 
houses  at  the  time  of  Philip  Augustus.  The  crania  must,  there- 
fore, at  the  latest,  date  from  the  twelfth  century,  many  of  them 
possibly  from  the  Carlovingian  period.  They  certainly  belonged 
to  individuals  of  the  higher  ranks,  as  they  were  found  in  closed 
vaults." 

The  average  capacitj  of  115  of  these  twelfth-century 
skulls  was  found  to  be  1425*98  cubic  centimetres. 

Another  series  of  skulls  was  obtained  from  the  Cime- 
tiere  de  1' Quest,  which  was  used  as  a  cemetery  from 
1788  to  1824.  Of  these,  which  may  be  called  skulls 
of  the  nineteenth  century,  as  many  as  125  were  ex- 
amined, and  they  yielded  an  average  capacity  of  1461*53 
centimetres. 

lifis  not  without  interest,  therefore,  to  find  that  in  the 
course  of  seven  centuries  of  progressive  civilization  the 
average  Parisian  skull  seems  to  have  distinctly  increased 
in  capacity. 

It  is,  moreover,  a  remarkable  fact,  as  Vogt  points  out, 
**  that  the  difference  between  the  sexes  as  regards  the 
cranial  capacity  increases  with  the  development  of  the 
race,  so  that  the  male  European  excels  much  more  the 
female  than  the  Negro  the  Negress." 

Le  Bon  also  has  quite  recently  stated*  that  the  differ- 
ence existing  between  the  average  capacity  of  the  skulls 
of  male  and  female  modern  Parisians  is  almost  double 
that  which  obtains  between  the  skulls  of  male  and  female 
inhabitants  of  ancient  Egypt. 

This  again  is  to  be  regarded  as  interesting  evidence  of 

♦  "  Compt.  Eend.,"  July  8,  1878,  p.  80.  Since  this  chapter  haa 
heeii  in  the  hands  of  the  printer  a  longer  paper  has  appeared,  by 
Le  Bon,  in  the  licvue  d'Anthropologie,  January,  1879. 


852  THE    SIZE    AND    WEIGHT 

the    effects    of    civilization   in    leading   to    an   increased 
development  of  the  Brain,  for,  as  Vogt  remarks, — 

"The  lower  the  state  of  culture,  the  more  similar  are  the  occa- 
pations  of  the  two  sexes.  Among  the  Australians,  the  Bushmen, 
and  other  low  races,  possessing  no  fixed  habitations,  the  wife  par- 
takes of  all  her  husband's  toils,  and  has,  in  addition,  the  care  of 
the  progeny.  The  sphere  of  occupation  is  the  same  for  both  sexes; 
■whilst  among  the  civilised  nations  there  is  a  division  both  in 
physical  and  mental  labour.  If  it  be  true  that  every  organ  is 
strengthened  by  exercise,  increasing  in  size  and  weight,  it  must 
equally  apply  to  the  brain,  which  must  become  more  developed 
by  proper  mental  exercise." 

Again,  it  has  been  pointed  out  by  Le  Bon  that  the 
range  of  variation  in  '  cranial  capacity  '  to  be  met  with 
among  different  individuals  of  the  male  sex  seems  to 
be  great  in  proportion  to  the  position  of  the  race  in  the 
scale  of  civilization.  '*  Thus  large  and  small  male  skulls 
among  Negroes  may  vary,"  he  says,  "  by  204  cubic  centi- 
metres, among  the  ancient  Egyptians  by  353,  among 
twelfth-century  Parisians  by  472,  and  among  modern 
Parisians  by  593  cubic  centimetres."  Consequently  he 
holds  that  the  real  test  of  superiority  of  one  race  over 
another  in  regard  to  *  cranial  capacity  '  is  not  to  be  ascer- 
tained by  averages,  which  may  be  and  often  are  most 
deceptive,  but  rather  by  discovering  how  many  individuals 
per  cent,  for  different  races  possess  skulls  of  given 
volumes.  "  The  superior  race,"  according  to  Le  Bon, 
*'  contains  many  more  voluminous  skulls  than  the  inferior 
race.  Out  of  100  modern  Parisian  skulls,  there  will  be 
about  11  specimens  whose  capacity  ranges  from  1700  to 
1900  cubic  centimetres,  while  among  the  same  number  of 
Negro  skulls  not  a  single  one  will  be  found  possessing  the 
capacities  above  mentioned."  In  his  more  recent  and 
longer  paper  Le  Bon  gives  the  following  interesting  table 
of  percentages  in  illustration  of  these  views  : — 


Chaj.  XX.] 


OF    THE    HUMAN    BRAIN. 


853 


Ckaniai  Capacity  in  Different  Human  Races. 


Cranial  Capacity. 

Modern 
Parisians. 

Parisians 

of  the  \2h 

Century. 

Ancient 
Egyptiann. 

Negroes. 

ATistra- 
lians. 

Cubic  Centimetres. 

1200  to  1300   .    . 

0-0 

0-0 

0-0 

7-4 

45-0 

3300  to  1400   .    . 

10-4 

7-5 

121 

35-2 

25-0 

1400  to  1500   .    . 

14-3 

37-3 

42-5 

33  4 

20-0 

1500  to  1600   .    . 

46-7 

29-8 

36-4 

14-7 

10-0 

1600  to  1700  .    . 

16-9 

20-9 

9-0 

9-3 

0-0 

1700  to  1800   .    . 

6-5 

4-5 

0-0 

0-0 

0-0 

1800  to  1900  .    . 

5-2 

0-0 

0-0 

0-0 

0-0 

The  same  writer  adds  :* — "  The  cranial  capacity  of  the 
Gorilla  often  reaches  600  cubic  centimetres,  so  that  it 
follows  that  there  are  a  large  number  of  men  more  allied 
by  volume  of  brain  to  the  anthropoid  apes  than  they  are 
to  some  other  men." 


Brain-Weights. 

The  mode  of  weighing  the  Brain  has  not  always  been 
similar  by  different  observers.  Some  have  been  accus- 
tomed to  strip  off  its  thin  enveloping  membranes  before 
putting  the  organ  into  the  scales,  while  others  weigh  it 
and  them  together.  But  the  weight  of  '  arachnoid  '  and 
*  pia  mater '  is  pretty  well  known,  and  would  scarcely 
exceed  |  or  1  oz.  Again,  of  those  who  follow  the  latter 
and  by  far  the  most  common  method,  some  have  weighed 
the  brain  in  its  entire  condition  almost  as  soon  as  it  has 
been  removed  from  the  body ;  while  one  observer  at  least, 
Dr.  Thurnam,  has  been  in  the  habit  of  slicing  it  first  and 
allowing  serum  and  blood  to  drain  away  for  one  to  two 

*  Loc.  cit.,  p.  75. 


854  THE    SIZE   AND    WEIGHT 

hours  before  putting  the  organ  into  the  scales.  By  this 
latter  process  its  total  weight  may  in  some  cases  be 
diminished  by  from  1  to  2  oz.* 

These  being  almost  the  only  possible  sources  of  varia- 
tion, where  ordinary  care  is  exercised  in  the  process  of 
weighing,  the  Brain-weights  of  different  observers  are 
more  strictly  comparable  with  one  another  than  are  the 
estimations  of  *  cranial  capacity  '  by  different  observers, 
using,  as  they  mostly  have  done,  very  different  methods, 
whose  relative  indices  of  variation  have  not  yet  been 
determined. 

Of  course  most  of  the  causes  which  affect  the  cranial 
capacity  of  individuals  would  also  affect  their  Brain- 
weights,  and  vice  versa.  But,  except  in  regard  to  the 
comparison  of  ancient  with  modern  races,  these  con- 
ditions have  been  much  more  fully  worked  out  in  terms 
of  Brain-weight  than  in  terms  of  cranial  capacity. 

Some  of  the  principal  modifying  conditions  will  now  be 
briefly  referred  to. 

Age. — It  was  believed  by  the  earlier  anatomists,  and 
even  by  Tiedemann  and  Sir  William  Hamilton,  that  the 
human  brain  attained  its  greatest  development  at  about 
the  seventh  year.  We  now  know  this  to  be  incorrect ;  yet 
from  the  extensive  researches  of  Dr.  Boyd  as  tabulated 
by  Thurnam  (loc.  cit..  Tab.  ix.),  it  would  appear  that  it 
does  in  the  male  actually  reach  about  -l^ths  of  its  ultimate 
weight  by  the  end  of  the  seventh  year,  and  in  the  female 
about  yjths  of  its  ultimate  weight  by  the  same  period. 
According  to  this  table,  moreover,  the  maximum  weight 
of  Brain,  for  both  sexes,  was  met  with  in  individuals  not 
exceeding  their  twentieth  year. 

♦  See  an  excellent  paper  by  Dr.  Thurnam."  On  the  Weight  of  the 
Human  Brain  and  on  the  Circumstances  affecting  it,"  Journ.  of 
Ment.  Science,  1806. 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  355 

Thurnam   from  a  careful  consideration  of   previously 
recorded  results  comes  to  the  following  conclusions : — 

"  It  may  in  general  be  admitted  that  the  average  weight  of  the 
brain  undergoes  a  progressive  increase  to  a  period  somewhere 
between  the  twentieth  and  fortieth  year.  According  to  all  the 
tables  before  us  which  refer  to  the  sane,  the  greatest  average 
weight  for  the  male  brain  is  that  for  the  middle  decennial  period, 
or  from  thirty  to  forty  years ;  and  this,  as  M.  Broca  observes, 
agrees  perfectly  with  what  we  know  of  the  continued  develop- 
ment of  intelligence  during  the  whole  of  this  period.  For  wotneu 
the  full  average  size  of  the  brain  is  perhaps  attained  within  the 
preceding  decade  of  twenty  to  thirty  years  ;  but  the  difference 
between  the  two  sexes  in  this  respect  is  not  great.  From  forty 
to  fifty  years  there  is  a  slight  diminution  in  weight  and  a 
greater  one  between  fifty  and  sixty.  After  sixty  years  the  rate 
of  decrease  is  still  greater;  the  process  of  decay  becomes  more 
and  more  rapid,  and  thus  in  the  eighth  decade  of  existence  the 
average  weight  of  the  brain  is  less  by  more  than  three  ounces  (80 
to  90  grammes)  than  it  was  in  the  fourth  decade.  In  the  aged,  on 
the  average,  the  weight  of  the  brain  decreases  '[lari  passu  with  the 
intelligence.  There  are  many  exceptions  to  this  general  law,  and 
some,  particularly  of  the  more  cultivated  and  learned  class,  pre- 
serve to  extreme  age  all  the  fulness  and  vigour  of  their  faculties. 
The  brain  of  such  men,  as  the  late  Professor  Gratiolet  observes, 
remains  in  a  state  of  perpetual  youth,  and  loses  little  or  none  of 
the  weight  which  belonged  to  it  in  the  prime  of  life." 

Sex. — Thurnam  says  : — "  My  own  observations  fully 
confirm  those  of  preceding  writers  as  to  the  average 
weight  of  the  adult  male  brain  being  about  ten  per  cent, 
greater  than  that  of  the  female.  As  Professor  Welcker 
expresses  it :  '  The  brain- weight  of  the  male  (1390  grmm.) 
is  to  that  of  the  female  (1250  grmm.)*  as  100 :  90.' 
Slight  variations  are  observable  in  the  brain-weights  of 
the  two  sexes,  as  given  by  different  observers,  but  it  will 
be  seen  that  the  average  difference  is  expressed  with 
much  accuracy  by  these  figures." 

*  That  is  about  49  oz.  and  44  oz.  respectively. 


85(5  THE    SIZE    AND    WEIGHT 

The  difference  between  the  average  weight  of  the  male 
and  female  brain,  according  to  Welcker's  compulation,  is 
4*94  oz.  or  140  grmm. ;  but  according  to  Dr.  Peacock's 
observations  on  the  Scotch,  5*3  oz.  or  150  grmm. 

Thurnam  says : — 

"  Some  have  supposed  with  Tiedetnann  that  the  less  size  of  the 
brain  of  the  female  is  due  simply  to  her  less  stature.  This,  how- 
ever, is  not  the  case  ;  and  it  was  long  ago  shown  by  M.  Parchappe, 
though  from  a  too  restricted  number  of  weights, that  the  difference 
was  greater  than  could  be  accounted  for  in  this  way.  I  am  able  to 
confirm  this  opinion  from  calculations  founded  on  the  great  tables 
of  Dr.  Boyd  for  St.  Marylebone.  For  this  purpose  I  have  examiued 
and  compared  the  average  stature  and  brain-v.-eight  for  Uien  and 

women  at  the  decennial  periods  from  twenty  to  sixty 

Whilst  the  brain-weight  is  nearly  10  per  cent,  less  in  the  female 
tlian  in  the  male,  the  stature  is  only  8  per  cent.  less.  '* 

Weight  of  Body  and  Stature.- — The  ratio  of  Brain- 
weight  to  body-weight  follows  almost  precipcly  the  same 
laws  as  have  been  found  to  hold  for  lower  animals ;  that 
is,  the  ratio  diminishes  with  increasing  weight  and  stature 
of  body,  so  that,  as  Tiedemann  observed,  ''the  human 
brain  is  smaller  in  comparison  to  the  body  the  nearer 
man  approaches  to  his  full  growth." 

It  varies  also  with  his  degree  of  obesity.  *'Di  lean  per- 
sons the  ratio  is  often  as  1 :  22  to  27  ;  in  stout  persons  as 
1 :  50  to  100." 

But,  as  Thurnam  says  : — **  Though  it  may  be  ques- 
tioned whether  many  useful  physiological  inferences  are 
to  be  deduced  from  the  ratio  of  the  brain-weight  to  that 
of  the  body  in  the  two  sexes,  the  comparison  of  the  brain- 
weight  with  the  stature  may  yield  more  valuable  conclu- 
sions. .  .  .  Parchappe  inferred  that,  other  things  being 
equal,  the  weight  of  the  brain  in  both  sexes  is  relatively 
greater  in  tall  persons  than  in  short  ones,  the  difference 


Chap.  XX]  OF    THE    HUMAN    CRAIN.  857 

between  the  two  being  at  tbe  rate  of  five  per  cent.  ;  i.e, 
the  brain  of  a  tall  man  being  represented  by  100,  that  of 
a  man  of  short  stature  was  95.  The  difference  in  women 
was  a  little  less."  This  agrees  pretty  closely  with 
Marshall's  more  recent  computations. 

Race. — Comparatively  few  observations  have  as  yet 
been  instituted  in  reference  to  this  very  large  subject — • 
viz.  the  question  of  the  average  or  prevailing  weight  of 
the  Brain  in  different  races  of  Men.  More  has  been 
done  in  this  direction  in  regard  to  variations  of  *  cranial 
capacity.' 

Some  sort  of  commencement  has,  however,  been  made 
towards  ascertaining  the  average  weight  of  Brain  for  the 
English  and  Scottish,  and,  with  less  precision,  that  for 
the  French  and  German  people.  But  the  observations 
made  have,  as  yet,  been  obtained  from  too  restricted 
areas,  and  too  much  from  persons  of  the  same  social  and 
educational  status. 

Thurnam  thinks  that  Welcker's  estimate  of  1390 
grammes  or  49  oz.  represents  the  mean  weight  of  male 
European  brains,  in  persons  of  twenty  to  sixty  years 
of  age,  with  considerable  accuracy,  and  he  gives  the 
following  table  showing  how  the  mean  brain- weights 
for  the  separate  people  above  mentioned  stand  in  regard 
to  it : — 

Eatio  of  Brain- Weight  of  different  European  Peoples. 


Males. 

Ounces. 

Grammes. 

Ratio  of  Brain-We 

Europeans  {Welcker)  .         . 

49 
478 

1390 
1354 

.      100 

English  {Boyd) 

.           .        97 

„       {Peacock)  .         , 

49 

1388 

.      99 

French  {Parchappe) 

47-9 

13-58 

.        .      98 

Germans,  &c.  (Wagne7-) . 

48-3 

1371 

.        .      98-5 

Scutch  {Peacock)     . 

50 

1417 

.        .    102 

858  THE    SIZE    AND    WEIGHT 

It  will  be  interesting  to  place  next  to  this  the  table 
given  by  Thtirnam  embodying  the  average  results  of  the 
weighing  of  twelve  Negro  brains. 

Average  Brain-Weight  or  Europeans  and  Negroes  Compared. 

Males.  Ounces.  Grammes.  Ratio  of  Brain-Weight. 

Europeans.         ...      49  1390    .         .     100 

Negroes  {Tiedeynann,  4<)  .  44-2  1252  .  .  90 
„  {Peacock,  6) .  .  44-3  1255  .  .  90 
5,         {Barhow,^).        ,     44-6       1261     .        .      90 

(Average,  12)        .     44-3      1255    .        .      90 

These  observations,  as  Thurnam  says,  agree  in  *'  making 
the  Brain- weight  of  the  male  Negro  the  same  as  that  of 
the  female  European."  He  adds  : — "  The  decided  influ- 
ence of  race  on  the  weight  of  the  brain  is  scarcely  to  be 
questioned ;  and  there  can  be  little  doubt  that  the  smaller 
size  of  the  brain  in  other  melanous  and  lower  races  will 
hereafter  be  made  out  by  direct  observation.  The  brains 
of  the  Hindoo,  Hottentot,  Bushman,  and  Australian,  are 
probably  of  less  weight  even  than  that  of  the  Negro; 
but  in  all  these  comparisons  the  stature  must  be  con- 
sidered." * 

Records  of  the  Brain- weight  of  males  belonging  to 
these  latter  races  are  not  as  yet  forthcoming ;  but  from 
the  ascertained  weight  of  three  female  Bushwomen,  as 
well  as  from  what  we  know  of  the  cranial  capacity  of  the 
races  mentioned,  it  may  fairly  be  anticipated  that  their 

*  Tlicre  is  some  reason  to  believe  that,  to  a  certain  extent,  as  we 
go  northwards  the  average  human  stature  increases,  and  with  it 
the  average  cranial  cajac  ty  and  brain-weight.  Yet  the  Lipps 
and  Esquimaux  are  extremely  short,  though  their  cranial  capacitiea 
remain  unusually  high. 


CiAP.  XX.]  OF   THE    HUMAN    BRAIN.  359 

weight  of  brain  would  fall   distinctly  below  that  of  the 

Negro. 

The  brain  of  a  Bushwoman  examined  by  Professor  Marshall  was 
computed  to  be  31'5oz.,  while  he  has  calculated  that  the  brain  of 
an  average  Englishwoman  of  about  the  same  age  and  stature 
ivould  have  weighed  not  less  than  40  oz.  The  brain  of  another 
Bushwoman,  commonly  known  as  the  "  Hottentot  Yenus,"  who  was 
examined  by  Gratiolet,  is  said  to  have  been  a  trifle  larger,  though 
the  exact  weight  was  not  ascertained.  Lastly — though  first 
in  order  of  time — Dr.  Quain  recorded  the  weight  of  a  Bosjes  girl, 
fourteen  years  of  age,  and  forty  inches  in  height,  as  34  oz.,  or  963 
grammes.  This,  as  Dr.  Thurnara  points  out,  "  falls  short  even  of 
the  average  weight  of  the  brain  of  the  female  English  child  between 
two  and  four  years  of  age,  in  whom,  according  to  the  tables  of  Dr. 
Boyd,  the  brain- weight  is  34"97  oz.  (991  grammes),  and  the  average 
stature  31'6  inches."  Seeing,  moreover,  as  Dr.  Boyd's  tables  also 
show,  that  by  the  end  of  the  seventh  year  the  brain  of  the  female 
has  attained  to  at  least  ten  elevenths  of  its  full  weight,  the  brain  of 
this  Bosjes  girl  is  not  likely  to  have  been  much  behind  the  weight 
to  which  it  might  have  attained  in  the  adult  condition. 

The  Chinese  are  representatives  of  the  most  ancient 
and  persistent,  if  not  the  most  advanced  civilization  of  the 
world,  and  quite  recently  the  brain-weights  of  eleven  aduil. 
males  and  of  five  adult  females  have  been  recorded  by 
Dr.  C.  Clapham.*  "  With  the  exception  of  one  indi- 
vidual they  all  belonged,"  he  says,  *'  to  the  *  Coolie,'  or 
lowest  grade  of  Chinese  society,"  yet  their  brain-weights 
were  remarkably  high,  when  it  is  considered  that  they 
were  in  no  way  picked  individuals,  but  mere  chance  vic- 
tims of  the  great  typhoon  which  raged  at  Hong  Kong  in 
September,  1874.  The  possible  influence  of  Congestion, 
owing  to  the  mode  of  death,  in  slightly  raising  these 
brain-weights  must,  however,  not  be  forgotten. 

•  "Journ.  of  the  Anthropolog.  Inst., "vol.  vii.  p.  90, 


860 


THE    SIZE    AND    WEIGHT 


Brain- Weights  of  Sixteen  Chinese. 


Males. 


No. 

Probable  Age 

.     Weight. 

1  .     . 

.  30  .     . 

.  49f 

2  .     . 

.  28  .     . 

.  50 

3  . 

.  45  .     . 

.53i 

4  ; 

.  40  .    . 

.  56 

6  . 

.    .  50  .    . 

.491 

6  . 

.     .  40  .    , 

,    .  48 

7  . 

.     .  25  . 

.    .  46| 

8  . 

.    .  48  . 

,    .  54 

9  . 

.    .  55  . 

.    .49^ 

10  . 

.    .  35  .    , 

.  511 

11  . 

,    .  30  . 

.    .46i 

Avera' 

Te  50-45 

Females. 


^0. 

JL'  ointbvvo. 
Probable  Age. 

Weight. 

1 . 

.    .  26  .    . 

.  45| 

2  . 

.    .  38  .    . 

.  49 

3  . 

.    .  30  .    . 

.  44 

4  . 

.    .  70  .    . 

.  42i 

5. 

.    .  18  .    . 

.  46i 

Average  45*45 


The  significance  of  these  figures  will  hereafter  he  re- 
ferred to. 

Mental  Power  and  Degree  of  Education. — Under 
this  head  we  may  hriefly  pass  in  review  what  is  known  as 
to  the  correlation  in  the  human  suhject  of  Intelligence 
and  degree  of  Education,  with  size  and  weight  of  Brain. 
Many  more  facts  are  needed  before  much  light  can  be 
considered  to  be  thrown  upon  this  subject ;  and,  moreover, 
some  of  the  data  at  present  in  our  possession  seem  at 
first  sight  rather  contradictory.  The  contradiction  is, 
however,  more  apparent  than  real. 

Some  hints  have  already  been  given  upon  this  subject, 
in  what  has  been  said  as  to  the  greater  capacity  of  skull 
and  weight  of  Brain  in  uncivilized  as  compared  with  civi- 
lized races,  and  also  in  reference  to  the  greater  cranial 
capacity  of  Parisians  of  the  nineteenth  as  contrasted  with 
those  of  the  twelfth  century.  Other  facts  having  the  same 
general  bearing  may  now  be  referred  to.      It  was,  for 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  361 

instance,  ascertained  by  Dr.  Thurnam,  that  the  average 
brain-weight  of  insane  males  belonging  to  the  more 
educated  middle  class  in  the  York  Retreat  was  decidedly- 
above  that  of  paupers  who  died  in  the  county  asylums  of 
Somerset  and  Wilts.*  Broca  has  also  made  some  inves- 
tigations in  order  to  ascertain  the  dimensions  of  the  heads 
of  a  number  of  students  of  the  Ecole  de  Mddecine  as 
compared  with  those  of  a  number  of  servants  in  the  large 
hospital  of  the  Bicetre,  with  the  result  of  showing  a 
distinct  preponderance  in  favour  of  the  students.  This 
latter  statement  is,  however,  not  easy  to  understand, 
unless  we  are  to  believe  that  the  superior  education  of 
the  students  has,  during  their  own  individual  lives,  given 
rise  to  a  distinctly  increased  size  of  Brain  and  of  head. 
Among  the  ancestors  of  the  students  and  the  servants  it 
is  quite  possible  that,  in  many  instances,  the  relative 
degree  of  education  and  amount  of  habitual  exercise  of 
brain  may  have  been  reversed.  If  Broca  could  measure 
the  heads  of  these  two  sets  of  persons  again — that  is  the 
same  individuals — after  an  interval  of  ten  years,  the 
relative  difference  between  these  two  measurements  of 
the  two  classes  might  yield  some  interesting  information. 
But  would  any  difference  be  observed  in  the  two  sets  of 
measurements  after  such  an  interval,  and  if  so  could  it  be 
ascribed  to  the  effects  of  superior  brain  exercise  ?  These 
very  doubtful  questions  remain  to  be  solved. f 

*  The  difference  was  not  nearly  so  well  marked  between  the 
brain-weights  of  the  females  of  these  two  classes;  a  fact  harmonious 
with  others  already,  and  subsequently  to  be,  cited,  showing  that 
the  range  of  variation  in  them  under  the  influence  of  various  con- 
ditions is  less  than  it  is  for  the  brain  of  men. 

f  Le  Bon  has  also  given  a  table  showing  the  prevailing  circum- 
ferential Head  measurements  (which  ranged  from  52  to  62*5  centi- 
metres) of  individuals  belonging  to  different  social  classes,  at 
present    living    in    Paris,    and    who,    from    their    differences    in 


362 


THE    SIZE    AND    WEIGHT 


Any  considerable  number  either  of  Skulls  or  Brains  will 
generally  be  found  to  contain  representatives  of  three 
artificial  series  into  which  it  is  convenient  to  divide  them. 
First,  those  of  medium  capacity  or  weight ;  second,  those 
which  are  more  or  less  decidedly  small  (microcephalous) ; 
third,  those  which  are  more  or  less  decidedly  large  (mega- 
locephalous).  For  Brain-weights  Thurnam  has  fixed  upon 
the  following  numbers,  as  those  most  expedient  to  adopt 
in  the  separation  of  such  classes  from  one  another. 


Microcephalous 

Brains  op 

Medium 

Meualocephalous 

Brains. 

Size 

• 

Brains. 

a. — Incipient  Micro- 

Men.  — 

-40-5 

2^    oz.    or 

a. — Incipient  Megalo- 

cephaly. 

1130- 

-1490 

grammes. 

cc/'lialy. 

Men.  —  40-37^    oz.     or 

Women 

-35- 

-47i  oz.  or 

Men. — 52| — 55  oz.    or 

1130-1062  grammes. 

990-1345  grammes. 

1490-1560  grammes. 

Women.— 35-321  oz.    or 

Women. — 47^-50  oz.  or 

990-920  grammes. 

1345-1417  grammes. 

6. — D  cidal  Micro- 

h.—Dec'ded  Megalo- 

cepJmhj. 

cej^kahj. 

Men. — Under  37^  oz.  or 

Men.— 55    oz.    or    1560 

1062  grammes. 

grammt.s,aiid  upwards. 

Women.— Under  32^  oz. 

Women.  —  50     oz.       or 

or  920  grammes. 

1417     grammes,    and 
upwards. 

This  is  a  useful  table,  since  it  shows  the  wide  range 
of  variation  to  be  met  with  in  the  brain-weights  both  of 
Men  and  of  Women ;  it  may,  however,  be  supplemented 
by  the   conclusions  of  Dr.    Sharpey  as   deduced  from    a 

mode  of  life,  are  accustomed  to  exercise  their  Intelligence  in  dif- 
ferent degrees.  The  prevailing  measurements  show  a  distinct 
decrease  in  the  order  of  his  four  classes,  whom  he  designates : — 
1,  Savants  et  lettres;  2,  Bourgeois  Parisiens;  3,  Nobles  d'au- 
cicnnes  families;    i,  DomestiqUes  Parisiens." 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  863 

careful  tabular  analysis  made  b}-  him  of  the  brain-weights 
recorded  by  Sims,  Clendinniug,  Tiedemann  and  Reid. 
Having  rejected  from  his  table  all  those  cases  in  which 
cerebral  disease  is  reputed  to  have  existed,  Dr.  Sharpey 
says  : — 

"  According  to  tbis  table  the  maximum  weight  of  the  adult  male 
brain  in  a  series  of  278  cases  was  65  oz. ;  and  the  minimum  weight 
34  oz.  In  a  series  of  191  cases  the  maximum  weight  in  the  adult 
female  was  o6  oz. ;  and  the  minimum  31  oz. ;  the  difference  between 
the  extreme  weights  in  the  male  subject  being  no  less  than  31  oz.,  and 
in  the  female  25  oz.  The  weight  of  the  adult  male  brain  appears, 
therefore,  to  be  subject  to  a  wider  range  of  variety  than  that  of  the 
female.  By  grouping  the  cases  together  in  the  manner  indicated 
by  brackets,  it  is  found  that  in  a  very  large  proportion  the  weight 
of  the  male  brain  ranges  between  46  oz.  and  53  oz.,  and  that  of  the 
female  brain  between  41  oz.  and  47  oz.  The  prevailing  weights  of 
the  adult  male  and  female  brain  may  therefore  be  said  to  range 
between  those  terms ;  and  by  taking  the  mean  an  average  weight 
is  deduced  of  49^  oz.  for  the  male,  and  of  44  oz.  for  the  female 
brain, — results  which  correspond  closely  with  the  statements  gene- 
rally received.  .  .  .  The  general  superiority  in  absolute  weight 
of  the  male  over  the  female  brain  is  shown  by  Table  2  to  exist  at 
every  period  of  life.  In  new-born  infants  the  brain  was  found  by 
Tiedemann  to  weigh  14^  oz.  to  15|  oz.  in  the  male,  and  10  oz.  to 
13^  oz.  in  the  female." 

{a) — Some  of  the  Conditions  coinciding  wnh  low  Brain- 
IV eights  : — The  average  brain-weight  of  persons  dying  in 
Lunatic  Asylums  has  been  found  to  be  distinctly  lower 
than  that  of  persons  of  the  same  class  who  are  not 
insane.  Some  of  this  diminution  of  the  average  brain- 
weight  among  the  insane  generally,  is  doubtless  due,  as 
Thurnam  suggests,  to  partial  atrophy  of  the  convolu- 
tions ;  though  some  of  it  may  also  be  attributable  to  initial 
smallness  of  brain  in  certain  of  the  representatives  of  this 
asylum  class.  But,  as  the  same  writer  remarks, — "  The 
average  brain-weight  of  those  dying  in  asylums  is  made 


804  THE    SIZE    AND    WEIGHT 

up  of  weights  which  are  above  the  average  of  the  healthy 
brain,  and  of  others  which  are  materially  below  it."  In 
general  the  latter  greatly  preponderate,  and  therefore  it  is 
that  the  average  is  low ;  but  among  Epileptics  in  asylums, 
and  occasionally  among  simply  demented  patients,  the 
brain  has  not  unfrequently  been  found  to  be  considerably 
above  the  normal  or  average  weight  for  sane  individuals. 

In  congenital  Imbeciles  and  Idiots  the  average  weight 
of  the  brain  is  still  lower  than  it  is  among  those  in  whom 
Chroniclnsanity  has  supervened  during  adult  life.  From 
an  examination  of  twenty-two  brains  of  idiots,  some  of 
whom  were  also  epileptics.  Dr.  Thurnam  obtained  an 
average  weight  for  fourteen  males  of  42  oz.,  or  1,190 
grammes,  and  for  eight  females  a  weight  of  41*2  oz.,  or 
1,167  grammes.  The  average  of  the  latter  is  curiously 
enough  almost  identical  with  that  of  the  rest  of  the 
female  insane  of  the  same  series;  though  that  of  the 
male  brains  is  very  decidedly  less.  Idiocy  is,  therefore, 
not  necessarily  associated  with  a  very  small  size  of  brain : 
though  this  is  frequently  the  case,  still  various  deficiencies 
in  the  internal  structure  and  finer  development  of  the 
brain  may  also  entail  a  similar  condition  of  mental  defect. 

Among  50  "brains  of  Idiots  examined  by  Dr.  Langdon  Down,  whose 
ages  ranged  from  5  to  33  years,  the  minimum  weight  in  a  boy  of  38 
was  15  oz.  (425  grammes) ;  the  maximum  weight  in  a  man  of  22 
was  as  much  as  59'5oz.  (1,404  grammes).  The  latter  weight  was 
in  all  probability  one  which  had  been  augmented  to  a  considerable 
extent  by  morbid  tissue  changes  of  a  kind  to  whic\i  reference  will 
presently  be  made. 

Where  the  weight  of  the  Brain  falls  below  a  certain 
minimum  standard,  the  possession  by  its  owner  of  anj'^- 
tbing  like  ordinary  Human  Intelligence  seems  to  be 
impossible.  Gratiolet,  without  specifying  the  sex,  sup- 
posed this  lower  limit  of  weight  to  be  about  3LJ  oz.,  or 


Chap.  XX.] 


or    THE    HUMAN    BRAIN. 


8G5 


900  grammes.  Broca  places  it  somewhat  higher,  fixing 
upon  32  oz.,  or  907  grammes,  as  the  limit  for  the  female, 
and  37  oz.,  or  1,049  grammes,  as  the  lower  limit  of 
weight  for  the  male  brain,  compatible  with  ordinary 
Human  Intelligence. 

The  brain-weight  of  Idiots  may,  however,  and  frequently 
does,  fall  far  below  the  limits  above  assigned,  and  that 
either  from  atrophic  disease  ensuing  some  time  after  birth 
or  from  congenital  defect.  Subjoined  is  a  table  given  by 
Thurnam  of  the  lowest  fifteen  brain-weights  as  yet  re- 
corded among  Idiots:* — 

Brain-Weights  of  Small-Headed  Idiots. 


Males. 

Females 

No.    Observer. 

Age.  Weight  of  Brain. 

No.    Observer. 

Age.  Weight  of  Brain. 

Oz.    ( 

armni. 

Oz.     Grmm. 

1.  Thurnam 

.      29 

35-76  1013 

1.  Bucknill      . 

37 

32-5      921 

2 

.     22 

35-5 

1006 

2.  Sims  . 

12 

27         765 

3.  Parchapp 

3.    45 

34-2 

970 

3.  Parch  appe  . 

25 

25-4      720 

4.  Thurnam 

.    52 

32 

907 

4.  Tuke  . 

70 

22-75    644 

6.  Peacock 

.    11 

212 

600 

5.  Tiedemann. 

16 

19-9      563 

6.  Down. 

.    18 

15 

425 

6.  Gore  . 

42 

10         283 

7.  Owen . 

.    22 

13-12 

372 

8.  Theile. 

.    26 

10-6 

300 

9.  Marshall 

.    12 

8-5 

241 

(b) — Some  of  the  Conditions  coinciding  icitli  high  Brain' 
weights: — Very  low  brain-weights  are,  as  we  have  seen, 
only  consistent  with  Dementia  or  Idiocy.  Very  high 
brain-weights  may,  however,  be  met  with,  either  (1)  in 
association  with  these  same  morbid  conditions  or  among 
insane  persons  belonging  to  other  categories ;  (2)  in  very 
ordinary  sane  individuals ;  or  (3)  among  the  most  highly 
intellectual  members  of  societv.     That  the  latter   asso- 


*  Log.  cit.,  p.  29.     Eeferences  to  the  original  descriptions  of 
these  brains  are  cited. 


866  THE    SIZE    AND    WEIGHT 

ciation  sliould  be  encountered  is  harmonious  enough 
with  commonly  received  beUefs,  though  the  existence  of 
the  two  former  will  be  regarded,  at  first  sight,  as 
altogether  anomalous.  But  it  is  not  so  anomalous  as 
it  may  seem. 

(1.)  In  regard  to  associations  of  the  first  order  Thurnam 
found  that  in  about  10  per  cent,  of  the  males  and  7  per 
cent,  of  the  females  who  died  in  the  Wilts  County  Lunatic 
Asylum,  the  brain-weight  exceeded  the  upper  limit  of 
the  *' medium  size,"  viz.,  52J  oz.  and  47|- oz.  respec- 
tively ;  while  in  from  3  to  4  per  cent,  decidedly  megalo- 
cephalous  weights  were  met  with — that  is,  above  55  oz. 
and  50  oz.  respectively.  These  facts  agree  pretty  closely 
with  the  observations  more  recently  published  by  Dr.  C. 
Clapham,*  although  the  proportion  of  decidedly  megalo- 
cephalous  weights  was  found  by  this  latter  observer  to 
be  slightly  higher  in  his  larger  series  of  brain-weights 
obtained  from  a  more  northern  English  Asylum.  Thus, 
among  700  male  brains  there  were  no  less  than  43  the 
weight  of  which  was  55  oz.  and  upwards — and  of  these  4 
weighed  even  as  much  as  60-61  oz.f 

In  reference  to  the  brain-weights  met  with  in  the  Wilts 
Asylum,  Thurnam  says  : — 

"The  large  brains  above  reviewed  are  with  little  exception  those 
of  persons  in  the  labouring  or  artisan  class,  and  if  in  any  of  them 
there  was  an  unusual  degree  of  intelligence,  the  sphere  for  its 
exercise  must  have  been  very  limited.     The  heaviest  brain  weighed 

♦  West  Riding  Asylum  Reports,  vol.  vi.,  1876. 

f  Is  the  lower  percentage  of  decidedly  megalocephalous  brnina 
met  with  by  Thurnam,  to  be  accounted  for  by  the  difference  in 
geographical  area  from  which  the  above  two  sets  of  patients  were 
derived?  or  may  it  not  be  just  as  much  due  to  the  fact  that 
Thnrnam's  weighings  were  made  after  previous  slicings  and  pro- 
longed drainage  of  b  cod  and  serum  had  taken  place?  (see  p.  353.) 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  367 

by  me  (G2oz.,or  1,760  grammes)  was  that  of  an  uneducated  butcher, 
who  was  just  able  to  read,  and  who  died  suddenly  of  epilepsy  com- 
bined with  mania,  after  about  a  year's  illness The  heaviest 

brain-weight  recorded  by  Dr.  Bucknill  is  that  of  a  male  epileptic, 
aged  thirty-seven ;  and  in  this  instance  the  brain  weighed  64*5  oz., 
or  1,830  grammes,  which  was  the  weight  of  the  brain  of  the  cele- 
brated Cuvier.  With  one  exception  the  maximum  weight  observed 
byM.  Parchnppe  was  also  that  of  an  epileptic  man,  aged  thirty-one, 
in  whose  case  the  brain  weighed  61'3  oz.,  or  1,737  grammes.  The 
heaviest  female  hrain  of  which  I  find  any  mention,  is  recorded  by 
Dr.  Skae.  The  patient  was  not  epileptic,  but  laboured  under 
monomania  of  pride,  dying  at  the  age  of  thirty-nine  of  an 
exhausting  disease — phthisis.  The  hrain  had,  for  a  woman,  tha 
monstrous  weight  of  61'5  oz.,  or  1,743  grammes." 

It  is  possible  that  these  decidedly  heavy  Brain- weights 
may  be  met  with  in  a  slight  1}^  higher  ratio  among  the 
insane  than  among  the  sane  members  of  any  particular 
class,  and  this  for  the  following  reasons : — First,  Insanity 
is  a  condition  dependent  upon  various  morbid  states  which 
may  perhaps  be  said  to  be  equally  prone  to  occur  in 
large-brained  and  in  small-brained  individuals  ;  secondly, 
in  some  of  the  cases  of  this  disease,  with  or  without  the 
association  of  Epilepsy,  the  organ  or  considerable  parts 
of  it  tend  to  become  indurated,  owing  to  a  dispropor- 
tionate development  or  actual  overgrowth  of  the  lower 
and  functionally  inert  constituents  of  the  brain — its  mere 
connective  tissue  or  *  neuroglia  ' — just  as  other  organs  of 
the  hody,  the  liver  for  instance,  may  be  spoiled  function- 
ally though  actually  increased  in  bulk,  owing  to  a  similar 
connective  tissue  overgrowth.  This  is  a  condition  apt  to 
be  met  with  in  confirmed  Epileptics.  And,  thirdly,  should 
one  of  these  latter  patients  happen  to  die  in  a  fit,  great 
fulness  of  the  blood-vessels  of  the  brain  may  operate  as 
another  cause  tending  to  augment  the  brain- weight — as 
it  is  well  known  to  do  in  whatever  way  the  congestion 
may   have   been   produced.     Wagner  has  called  special 


308  THE    SIZE    AND    WEIGHT 

attention  to  this,  and  to  the  fact  that  brain-weights  are 
affected  not  only  by  length  and  kind  of  illness,  but  by 
mode  of  death.* 

(2.)  But  again,  high  Brain-weights  have  occasionally 
been  met  with  by  many  observers  in  the  examination  of  tho 
bodies  of  quite  ordinary,  common-place  individuals,  who 
during  life  have  neither  been  insane  nor  notable  foi  any 
unusual  degree  of  intelligence. 

Perhaps  the  largest  set  of  tables  from  which  we  can 
obtain  trustworthy  information  on  this  subject  has  been 
supplied  by  Dr.  Peacock,  and  concerning  these  Thurnam 
writes  : — 

"  In  Dr.  Peacock's  tables,  out  of  the  157  weights  of  brains  of 
adult  Scotchmen,  between  twenty  and  sixty  years  of  age,  there  are 
four  in  which  this  ranged  from  61  oz.  to  6275  oz.,  or  from  1,728  to 
1,778  grammes.  They  were  all  apparently  of  the  artisan  class; 
the  occupation  of  three  of  them  being  those  of  sailor,  printer,  and 
.tailor  respectively.  The  causes  of  death  were  fever,  delirium 
tremens,  and  in  two  cases  severe  compound  fracture.  All  were 
[affections]  more  or  less  liable  to  be  attended  with  cerebral  con- 
gestion ;  and  there  is  nothing  to  show  that  these  individuals  were 
distinguished  from  their  fellows  by  superior  endowments." 

The  heaviest  Human  Brain  as  yet  on  record  seems 
also  to  have  belonged  to  a  person  of  this  class.  A  brief 
account  of  it  has  been  pubHshed  by  Dr.  James  Morris.f 
The  man  from  whom  it  was  taken  was  a  bricklayer, 
thirty-eight  years  of  age,  who  died  from  pyiicmia  in 
University  College  Hospital  in  1849,  shortly  after  a 
surgical  operation. 

Dr.  Morris  says  : — "The  weight  of  the  brain,  taken  immediately 
on  removal,  exceeded  67  oz.  This  weighing  was  most  carefully 
made,  and  was  witnessed  by  several  students.  The  brain  was  well 
pro]3ortioned ;  the  convolutions  were  not  flattened,  though  the  sur- 

*  Vorstudien,  1862,  2t«  Abh ,  pp.  93-95. 

t  "  Brit.  Med.  Journ.,"  Oct.  26, 1872,  p.  465. 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  369 

face  was  fairly  moist ;  it  only  lost  about  one  ounce  weight  after  the 
usual  dissection  and  draining  for  two  hours."  The  man's  height 
was  five  feet  nine  inches,  and  he  was  of  a  robust  frame.  It  was 
difficult  to  obtain  any  satisfactory  history  of  him — his  wife  and  his 
landlady  gave  different  accounts.  It  seemed,  however,  that  ho 
was  a  native  of  Sussex ;  that  he  "  had  left  his  native  village  and 
changed  his  name  on  account  of  some  poaching  troubles ;  that  he 
■was  not  very  sober ;  had  a  good  memory,  and  was  fond  of  politics. 
He  could  neither  read  nor  write. "  Whatever  his  potentialities 
might  have  been,  therefore,  it  is  evident  that  his  actual  acquire- 
ments were  not  great. 

(3.)  The  comments  which  we  shall  have  to  make  on 
these  latter  cases  will  be  better  reserved  till  some  illustra- 
tions have  been  given  of  the  existence  of  high  Brain- 
weights  among  men  of  great  mental  powers  and  acquire- 
ments— some  of  whom  in  their  various  spheres  of  life  and 
occupation  have  been  among  the  foremost  representatives 
of  Human  Intelligence.  Subjoined  is  a  list  given  by 
Thurnam,  together  with  eight  additional  brain- weights, 
viz.,  those  of  Schiller,  Agassiz,  Professor  Goodsir,  Sir 
James  Simpson,  Mr.  Chauncey  Wright,  De  Morgan, 
Grote,  and  Dr.  Hughes  Bennett.* 

Brain-Weights  of  Distinguished  Men. 

Name.  Age.     Ounces.  Grammes. 

1.  Cuvier,  Naturalist       ...     63         64'5       1830 

2.  Ahercromhie,  Physician      .         .64         63         1785 

*  References  will  be  found  in  Dr.  Thurnam's  paper  for  the  place 
of  record  of  most  of  these  high  brain- weights  tabulated  by  him 
The  eight  additional  weights  here  given  have  been,  in  the  above 
order,  thus  referred  to,  published,  or  ascertained : — (1)  Schiller  and 
Agassiz,  by  Daniel  Wilson,  in  "  Canadian  Journal,"  Oct.  1876 ; 
(2)  Goodsir's  "Anatom.  Memoirs,"  vol.  i.  p.  195  ^1868);  (3)  "Med. 
Times  and  Gaz,"  May  14,  1870,  p.  532 ;  (4)  Thos.  Dwight  in 
"Proceed.  American  Acad,  of  Arts  and  Sciences,"  vol.  xiii.  (1878); 

(5)  Examination  made  by  Dr.  Wilson  Fox  and  the  writer  in  1871 ; 

(6)  Examination  by  Prof.  Marshall  in  1871 ;  (7)  "  Brit.  Med- 
Journ.,"  Oct.  9,  1873. 


370  THE    SIZE    AND    WEIGHT 

Name.  Age.     Ounces.  Grammes. 

3.  Schiller,  Poe^      . 

4.  Goodsir,  Anatomist     ,         • 
6.  Spurzheim,  Physician         , 

6.  James  Simpson,  PJiysician 

7.  Dirichlet,  Matltemati.cian   . 

8.  De  Moray,  Statesman 

9.  Daniel  Webster,  Statesman 

10.  Campbell,  Lord  Chancellor 

11.  Chauncey  Wright,  Physicist 

12.  Agassiz,  Naturalist     . 

13.  Chalmers,  Celebrated  Preacher 

14.  Fuchs,  Pathologist 

15.  De  Morgan,  Mathematician 

16.  Gauss,  Mathematician 

17.  Dupuytren,  Surgeon  .         • 

18.  Grote,  Historian  .        • 

19.  Whewell,  Philosopher.        . 

20.  Hermann,  Philologist 

21.  Hughes  Bennett,  Phijsician 

22.  Tiedemann,  Anatomist 

23.  Hausmann,  Mineralogist    , 

It  is  worthy  of  note  that  in  this  list,  in  addition  to 
the  great  proportion  of  high  Brain-weights,  there  are  also 
four  of  distinguished  men,  which,  even  after  allowance  has 
been  made  for  some  amount  of  atrophy  consequent  upon 
age  in  two  of  them,  would  more  or  less  distinctly  fall 
beneath  the  mere  average  weight  of  49  oz. 

The  facts  set  forth  in  the  ahove  tjible  as  well  as  those 
detailed  in  the  last  section,  are  principally  of  interest 
from  their  bearing  upon  the  much  and  long-debated 
question  as  to  the  existence  of  any  necessary  or  invariable 
connection  between  mere  size  or  ic eight  of  Brain  ami 
Intelligence.  Upon  this  subject  a  few  brief  remarks  may 
now  be  made. 

In  the  first  place  then,  it  seems  perfectly  plain  from  the 
facts   recorded  that  there  is  no  necessary  or   invariable 


46 

63 

1785 

53 

57-5 

1630 

56 

55-06 

1559 

59 

54 

1533 

54 

53-6 

1520 

50 

53-6 

1520 

70 

53-5 

1516 

80 

53-5 

1516 

45 

53-5 

1516 

m 

53-3 

1512 

67 

53 

1502 

52 

52-9 

1499 

73 

52-75 

1496 

78 

52-6 

1492 

58 

50-7 

1436 

76 

49-75 

1410 

71 

49 

1390 

51 

47-9 

1358 

63 

47 

1332 

80 

44-2 

1254 

77 

43-2 

1226 

Chap.  XX.]  OF    THE    HUMAN    BRAIN.  871 

relation  between  the  degree  of  Intelligence  of  human 
beings  and  the  mere  size  or  weight  of  their  Brains. 
We  have  seen  that  some  demented  persons  may  have 
very  large  brains  ;  and  again,  that  in  certain  very  ordinary 
members  of  society,  suffering  neither  from  disease  nor 
from  congenital  defect,  the  brain  may  be  decidedly  large 
and  heavy.  On  the  other  hand  men  of  great  acquire- 
ments, of  acknowledged  mental  power,  and  one  or  two 
even  of  European  fame,  may  have  been,  whilst  in  their 
prime,  possessed  of  brains  either  below  or  only  slightly 
exceeding  the  average  weight  of  the  male  brain  in  civilized 
races,  viz.,  49  oz. — showing  that  a  well- constituted  Brain  of 
small  dimensions  may  be  capable  of  doing  much  better 
work  than  many  a  larger  organ  whose  internal  constitution 
is,  from  one  or  other  cause,  defective. 

Looking,  in  fact,  to  the  mere  size  and  weight  of  a 
Brain,  it  must  never  be  forgotten  that  these  may  be 
notably  augmented  by  overgrowth  of  its  mere  inert  con- 
nective tissues;  or  even  if  morbid  tissue  changes  be 
absent,  that  an  organ  of  large  size  or  weight  may  yet  be 
a  more  or  less  inferior  perceptive  or  thinking  instrument 
by  reason  of  its  inner  and  finer  developments  being 
defective  and  badly  attuned  for  harmonious  action.  Or 
again,  it  may  be  a  defective  instrument  by  reason  of  some 
still  more  subtle,  and  mere  molecular  peculiarities  of  the 
nerve  elements  of  which  it  is  composed — whereby  these  are 
perhaps  both  less  receptive  and  less  '  retentive '  of  those 
Sensorial  Impressions  which  constitute  the  raw  material 
of  Intelligence,  and  also  less  capable  than  they  might  be 
of  taking  part  in  higher  Mental  Operations. 

There  is,  therefore,  no  invariable  or  necessary  relation 
between  the  mere  Brain-weights  of  individuals  and  their 
degrees  of  Intelligence.  But  should  it  be  asked  whether 
the  proportion  of  megalocephalous  Brains  among  highly 


372  THE    SIZE    AND    WEIGHT 

cultured  and  intelligent  people  is  likely  to  be  greater  tlian 
among  uncultured  and  non-intelligent  people,  the  answer 
to  this  question  may  be  unmistakeably  in  the  affirmative — 
and  this,  as  Le  Bon  has  pointed  out  in  regard  to  '  cranial 
capacities,'  is  the  real  direction  in  which  we  ought  to  look 
for  evidences  of  class  or  racial  superiority. 

This  modified  or  more  correct  form  of  an  old  notion  is 
based  upon  various  facts  which  give  it  a  very  distinct  sup- 
port. As  previously  stated,  the  proportion  of  'decidedly 
megalocephalous '  male  brains  has  been  found,  among 
the  lower  and  less  educated  members  of  society,  to  range 
between  4  and  6  per  cent,  for  persons  under  sixty  years 
of  age ;  while  in  the  above  table  of  Brain-weights  of 
Distinguished  Men  (which,  be  it  observed,  is  in  no  sense 
a  selected  list,  since  it  comprises  all  such  weights  known 
to  the  writer  as  having  been  recorded)  the  proportion  of 
those  exceeding  55  oz.  amounts  to  nearly  23  per  cent., 
and  might  have  been  much  larger  still  had  it  not  been 
for  the  great  age  of  some  of  the  distinguished  individuals 
whose  brains  were  examined.  For,  notwithstanding  a 
marked  amount  of  senile  atrophy  in  some  of  these  brains 
no  less  than  eleven  of  them  still  weighed  52|  to  55  oz. 
It  seems  quite  possible  that  those  of  Sir  James  Simpson, 
Daniel  Webster,  Lord  Campbell,  and  Professors  De 
Morgan  and  Gauss,  may  each  have  exceeded  55  oz.  in 
weight  when  these  distinguished  men  w^ere  not  only  in 
good  health  but  distinctly  under  sixty  years  of  age.  And 
in  this  case  the  number  of  '  decidedly  megalocephalous  ' 
Brains  among  these  twenty- three  Distinguished  Men 
would  be  raised  to  about  45  per  cent.  The  list  is  small 
from  which  to  draw  any  conclusions,  but  the  difference 
in  proportion  indicated  seems  to  be  for  too  great  to  be 
attributable  to  mere  chance. 

Apart  from  the  existence  of  actual  morbid  changes,  the 


Chap.  XX.]  OF    THE    HUMAN    BRAIN.  873 

large  size  of  an  organ  such  as  the  Brain  gives,  perhaps,  a 
more  than  average  warrant  that  its  inner  development  will 
he  adequately  carried  out,  and  that  the  organ  will  be  highly 
endowed  with  its  own  proper  kind  of  vitality.  If  how- 
ever it  does  not  fall  short  in  either  of  these  respects,  an 
increased  size  of  Brain  ought  to  be  a  distinct  advantage  for 
its  owner ;  and,  should  the  general  and  special  conditions 
of  life  be  at  all  propitious,  would  be  likely  to  favour  the 
development  of  great  Mental  Power  or  the  acquisition  of 
much  Learning. 

The  tendency  to  the  occurrence  of  high  Brain -weights  in 
much  larger  proportion  among  the  civilized  than  among 
uncivilized  or  little  civilized  races  has  been  already  referred 
to  in  this  chapter.  This,  together  with  the  other  most  note- 
worthy and  well-estabHshed  fact,  that  such  differences  of 
brain-weight  are  found  to  be  far  more  marked  among  the 
Men  than  among  the  Women  when  higher  and  lower  races 
are  compared,  affords  most  valuable  evidence  to  show  the 
extent  to  which  the  Human  Brain  has,  in  the  course  of 
many  generations,  gone  on  increasing  in  size  under  the 
influence  of  that  augmented  use  and  exercise  apt  to  be 
entailed  by  a  life  passed  in  a  state  of  Civilization. 

But  the  longer  a  state  of  Civilization  has  existed  among 
any  particular  people,  the  more  generally  diffused  among 
the  individuals  of  such  a  people  should  be  the  tendency 
to  inherit  a  brain  of  full  dimensions.  And,  except  it  be  due 
to  some  quasi- accidental  and  little  understood  race  distinc- 
tions, how  else  are  we  adequately  to  explain  the  remarkable 
series  of  Chinese  brain-weights  published  by  Dr.  C.  Clap- 
ham?  In  these  sixteen  chance  individuals  of  the  Coolie 
class  the  brain-weights  are  distinctly  above  the  average  for 
English,  French,  or  Germans,  of  the  same  social  grade, 
and,  though  to  a  less  extent,  also  above  that  for  Scottish 

Lowlanders. 

17 


374  THE    SIZE    AND    WEIGHT 

Be  the  cause  what  it  may  (and  their  mode  of  death 
must  not  be  forgotten),  it  would  scarcely  be  possible  to 
point  to  such  another  series  of  figures  for  any  sixteen 
chance  individuals — with  the  single  exception  of  those 
recorded  in  our  table  of  *  Brain- Weights  of  Distinguished 
Men.' 

It  is  not  at  all  necessary  to  suppose  that  the  individual 
Chinese  Coolies  were  capable  of  displaying  any  notable 
amount  of  intellectual  '  acquirement '  or  '  power,'  in  order 
to  justify  their  possession  of  such  large  brains.  Dr. 
Clapham  records  a  fact  of  some  significance  in  this  con- 
nection when  he  says : — "  Of  the  capacity  of  the  Chinese 
Coolie  class  for  learning  J  am  not  inclined  to  speak  so 
lightly,  but  on  the  contrary  am  convinced  of  their  natural 
aptitude  in  this  direction."  We  have  in  these  facts, 
perhaps,  just  what  might  be  expected  as  a  result  of  a 
very  long-continued  antecedent  civilization  even  of  a  low 
order,  viz.,  the  inheritance  of  a  Inrge  Brain  together  with 
a  good  aptitude  or  '  capacity  '  for  learning.* 

The  Brain  is  diiTerent  from  all  other  organs  of  the  body. 
It  is  often  a  mass  of  structural  potentialities  rather  than 
of  fully-developed  nerve  tissues.  Some  of  its  elements, 
viz.,  those  concerned  with  best-established  Instinctive 
Operations,,  naturally  go  on  to  their  full  development 
without  the  aid  of  extrinsic  stimuli ;  others,  however,  and 
large  tracts  of  these,  seem  to  progress  to  such  develop- 
ments only  under  the  influence  of  suitable  stimuli.  Hence 
natural  aptitudes  and  potencies  of  the  most  subtle  order 
may  never  be  manifested  by  multitudes  of  persons,  for 
want  of  the  proper  stimuli  and  practice  capable  of  per- 
fecting the  development  and  functional  activity  of  those 

*  See  pp.  351-353,  where  some  facts  are  mentioned  tending  to 
Bhow  that  Civihzation,  acting  through  long  periods,  does  help  to 
brinjT  about  an  increase  in  the  size  of  the  brain. 


CiiAP.  XX  ]  or    THE    HUMAN    BRAIN.  375 

regions  of  the  brain  whose  action  is  inseparably  related 
to  the  mental  phenomena  in  question. 

The  development  here  referred  to  is  of  the  finer  sort ; 
that  which,  to  some  extent,  eludes  our  present  means  of 
observation.  Its  establishment  may  be  associated  with 
an  altogether  insignificant  increase  of  weight,  and  perhaps 
no  increase  in  size,  of  the  organ  as  a  whole.  Yet  a 
development  of  previously  embryonic  Nerve  Cells,  together 
with  an  establishment  of  multitudinous  new  connections 
between  them,  by  means  of  *  intercellular  processes '  and 
'  commissural  fibres,'  may  have  been  taking  place  through- 
out large  tracts  and  areas  of  the  Brain,  to  an  extent  which 
it  is  altogether  impossible  for  us  adequately  to  realize.* 

That  this  is  no  mere  fancy  is  in  part  evidenced  by  other 
facts  previously  stated,  viz.,  that  the  male  brain  actually 
attains  -|ihs,  and  the  female  brain  yyths  of  its  total 
ultimate  weight  by  the  end  of  the  seventh  year — although, 
at  this  time,  the  inner  and  finer  structural  development 
of  the  organ  is,  in  all  its  higher  tracts,  still  in  a  com- 
paratively embryonic  condition.  Even  such  data  might, 
therefore,  be  considered  to  show,  in  the  strongest  manner, 
how  comparatively  unimportant  is  mere  bulk  or  weight  of 
Brain  in  reference  to  the  degree  of  Intelligence  of  its 
owner,  when  considered,  as  it  often  is,  apart  from  the  much 
more  important  question  of  the  relative  amount  of  its  grey 
matter,  as  well  as  of  the  amount  and  perfection  of  the 
minute  internal  development  of  the  organ  either  actual  or 
possible. 

*  See  p.  346,  for  the  statement  made  by  Lockliart  Clarke  as  to 
the  characteristics  of  the  embryonic  or  undeveloped  nerve  ele- 
ments met  with  in  the  Cerebral  Convolutions  of  the  tcetus. 


CHAPTER  XXL 

THE    EXTEENAL    CONFIGURATION    OF    THE    HUMAN   BRAIN. 

The  Brain  of  Man  belongs  to  the  same  type  or  pattern  as 
that  met  with  among  Apes  and  Monkeys.  Whatever  in- 
terpretation may  be  put  upon  it,  this  fact  itself  is  too 
obvious  to  admit  of  any  doubt.  The  same  general  shape 
is  to  be  seen,  the  same  lobes,  the  same  principal  fissures. 

It  is  true  that  important  differences  are  also  en- 
countered. The  relative  size  and  development  of  the 
several  Lobes  is  not  the  same.  There  is  again  in  the 
brain  of  Man  a  much  greater  richness  and  complicacy  of 
the  '  secondary '  fissures  and  Convolutions ;  whilst  a 
difference  eclipsing  all  others  in  importance  is  to  be  found 
on  the  side  of  weight.  The  maximum  Brain-weights  that 
have,  as  yet,  been  encountered  among  the  great  *  man- 
like '  Apes,  range  from  12-16  oz.,  although  the  body- 
weight  of  some  of  these  creatures  equals  or  may  even 
greatly  exceed  that  of  an  ordinary  Man. 

Striking,  however,  as  the  difference  is,  between  the 
brain-weights  of  the  great  *  man-like  '  Apes  and  those  of 
ordinary  human  beings,  it  must  not  be  forgotten  that  the 
actual  range  of  variation  met  with  among  individual  Men 
is  still  greater.  Some  persons  may  exhibit  distinctly 
human  attributes  and  mental  powers,  though  possessing 
brains  which  do  not  exceed  32  oz.  in  weight,  whilst  the 
same  organ  in  other  Men  may  rise  to  a  maximum  of 
64-67  oz.     Such  facts,  together  with  others  already  cited. 


Chap.  XXr.]  OF    THE    HUMAN    BRAIN.  377 

certainly  imply  the  existence,  in  the  Brain  of  Man,  of  a 
remarkable  capacity  for  growth  and  development,  under 
the  long-continued  influence  for  generation  after  genera- 
tion of  those  modes  of  life  and  cerebral  activity  which 
are  almost  inseparable  from  existence  in  a  more  or  less 
Civilized  Community. 

In   studying  the   external  configuration  of  the  Human 
Brain,  it  will  be  most  expedient,  in  the  first  place,  to  look 


V.Jt. 

Fig.  133.— Brain  of  the  Hottentot  Venus,  side  view.  (Vogt,  nfter  Gratiolet.) 
F,  Frontal  lobe  ;  P,  parietal  lobe ;  0,  occipital  lobe ;  T,  temporal  lobe  ;  C,  Cere- 
bellum ;  Po,  pons  Varolii  ;  V  M,  medvilla  oblongata  ;  S,  Sylvian  fissure  ;  R,  fissure  of 
Rolando ;  P  S,  parallel  fissure,  a',  Upper  fold  of  frontal  convolutions ;  o2,  middle 
fold  of  frontal  convolutions  ;  a^,  lower  fold  of  frontal  convolutions.  A,  Ascending 
frontal  (or  anterior  central)  convolution  ;  B,  ascending  parietal  (or  posterior  central) 
convolution  ;  b^,  b'i,  h^,  upper,  middle  and  lower  folds  of  parietal  convolutions ; 
c',  c2,  c^,  upper,  middle  and  lower  folds  of  temporal  convolutions  ;  d^,  d^,  di,  upper, 
middle  and  lower  folds  of  occipital  convolutions. 

to  the  characters  of  the  organ  as  it  exists  in  one  of  the 
lower  races  of  Mankind.  We  may  then  advantageously 
compare  one  of  these  simpler  types  with  the  more  highly 


378  THE    EXTERNAL    CONFIGURATION 

evolved   forms  of  the  same  organ,  such  as  are  common 
among  representatives  of  the  higher  civiHzecl  races. 

The  brain  of  the  so-called  '  Hottentot  Venus  '  was  care- 
fully examined 
and  figured 
by  Gratiolet. 
Though  her  in- 
telligence was 
not  notably 
defective,  the 
convolutions  of 
her  brain  were 
relatively  very 
little  compli- 
cated. After 
commentin  g 
upon  this  fact, 
Gratiolet  adds : 
— "  But  what 
strikes  one,  at 
once,  is  the  sim- 
plicity, the  re- 
gular  arrange- 

FiG.   134.— Brain  of    the   Hottentot  Venus,   upper    aspect.  l^lG^^t        01       tlie 
(Vogt,  after  Gratiolet.)  ^^y^         COUVOlu- 

L,  Longitudinal  fissure ;  Ji,  fissure  of  Rolando ;   V,  vertical     .  i  •    i 

or  perpendicular  fi.ssure  ;  0,  occipital  lobe,     o',  a-,  a3,  Upper,  tlOllS  WlllCn 

middle  and  lower  folds  of  frontal  convolutions  ;  A,  ascending    ,  xi 

frontal,   and  B,   ascending  parietal  convolutions ;  b\  m,  63,  ^^mpOSC 
upper,  middle  and  lower  folds  of  parietal  convolutions;  tP,  SUPCrior     an<^"le 
lower  fold  of  occipital  convolutions.  pi  i>        ^    t 

01  the  frontal 
lobe.  These  folds,  if  those  of  the  two  hemispheres  be 
compared,  present,  as  we  have  already  pointed  out,  an 
almost   perfect    symmetry,    such    as    is    never    exhibited 

by  normal  brains  of   the  Caucasian  race This 

regularity — this  symmetry,  involuntarily  recalls  the  regu- 


Chap.  XXL]  OF    THE    HUMAN    BRAIN.  379 

larity  and  symmetry  of  the  cerebral  convolutions  in  the 
lower  species  of  animals.  There  is,  in  this  respect, 
between  the  brain  of  a  white  man  and  that  of  this  Bos- 
jesman  woman  a  difference  such  that  it  cannot  be  mis- 
taken ;  and  if  it  be  constant,  as  there  is  every  reason  to 
suppose  it  is,  it  constitutes  one  of  the  most  interesting 
facts  which  have  yet  been  noted." 

The  most,  complete  description  we  at  present  possess, 
however,  of  the  Brain  of  a  representative  of  one  of  these 
lower  races  has  been  given  by  Prof.  Marshall  in  his 
Memoir  on  the  brain  of  a  Bush  woman.*  The  organ  in 
this  South  African  woman  was  decidedly  small,  as  will 
have  been  gathered  from  what  has  been  said  in  regard 
to  it  in  the  last  Chapter  (p.  359).  Certain  portions  of 
Marshall's  description  are  here  reproduced  in  his  own 
words. 

General  Shape  of  the  Cerebrum.  "  When  viewed 
from  above,  the  Bushwoman's  Cerebrum,  like  her 
cranium,  presents  a  long  and  narrow  ovoid  form.  The 
line  of  greatest  width  corresponds  with  the  parietal  emi- 
nences, and  is  placed  rather  far  back,  viz.,  at  two-thirds 
of  the  total  length  of  the  Cerebrum  from  its  anterior 
border,  so  that  one-third  only  is  behind  those  eminences. 
From  this  prominent  parietal  region  the  Cerebrum 
slopes  or  falls  away  in  all  directions — very  suddenly  back- 
wards and  rather  so  forwards  as  far  as  the  entrance  of  the 
Sylvian  fissure,  where,  like  the  foetal  brain,  it  appears 
remarkably  constricted,  and  then  widens  again  a  little  at 
the  outer  angles  of  the  frontal  region,  which  is  neverthe- 
less decidedly  narrow.  The  left  hemisphere,  as  seen  from 
above,  is  -2  of  an  inch  longer  than  the  right,  the  increase 
being   almost    entirely   behind.      This    relative    greater 

*  "Phil  Trans."  1864,  p.  501. 


380 


THE    EXTERNAL    CONFIGUllATION 


length  of  one    hemisphere  backwards   (usually   the   left, 

so   far  as  I  have  observed)  is  very  common   in  European 

brains." 

'*  Viewed  laterally  the  parietal  region  is  salient ;  the 

vertex  is  low  and  flattened,  its  highest  point  being  placed 

far  back  ;  the  frontal 
region  is  shallow." 
....  "The  tem- 
poral lobe  is  narrow, 
the  line  from  its 
point  to  the  tip  of 
the  posterior  lobe 
being  very  long  ;  the 
curve  formed  by  the 
under  border  of  the 
Cerebrum,  above 
the  Cerebellum,  is 
slighter,  and  its 
direction  more  ob- 
lique upwards  and 
backwards  than  in 
the  European  brain, 
owing  apparently 
to  a  want  of  down- 
ward     development 

3,  3,  upper fruntal  convolution;  4,  4,  ascending  frontal,     of    tllO     OCCipital    re- 
and  5, 5,  ascending  parietal  convolution  ;  5',  5',  lobule  of        .  l   •    l       ' 

ascending  parietal  convolution  ;  G,  G,  angular  convolu-    glOU     W'lllCn     IS     Very 

,   .   .  the 
tips  of  the  temporal 
lobes  are  pointed  and  much  incurved  towards  the  middle 

line The  orbital  surfaces  are  especially  contracted, 

but  have   a   square   or  human  and  not  a  pointed  or  ape- 
like shape." 

Taken  as  a  whole  this  brain  of  the  Bushwoman,  when 


Pig.  135.-  The  Brain  of  a  Bushwoman,  upper  as- 
pect.   (Heath,  after  Marshall.) 

F,  Frontal  loba ;  O,  occipital  lobe;  P,  parietal 
lobe  ;  d,  d,  fissure  of  Rolando ;  P,  parieto-occipital 
fissure  •,A,A,  supra-marginal  lobule.  2,  2,  Middle,  and 


tion  ;  10, 10,  upper,  and  11,  11,  lower  occipital  convolu-    gJ^alloW 
tion.  a,  a,  first,  and  /3,  second  connecting  convolutions. 


Chap.  XXL]  OF    THP:    HUMAN    BRAIN.  381 

compared  with  that  of  the  European,   was  found  to   be 
specially  defective  in  depth  and  vertical  height. 

Fissures,  Lobes,  and  Convolutions  of  the  Cere- 
brum. ''  The  fissure  of  Sylvius  in  the  Bushwoman's 
brain  extends  well  backwards,  but  inclines  more  upwards 
than  in  the  European  brain,*  and  its  course  is  marked 
soon  after  its  commencement  by  a  peculiar  horizontal 
step Its  mar/T^ins    are   not    very  closely  adapted 


Fig.  136.— The  Brain  of  a  Biishwoman,  lateral  aspect.  (Heath,  after  Marshall) 
Letters  and  figures  of  reference  in  part  as  in  last  figiue.  T,  temporal  lobe  ;  c.  island  of 
Reil ;  e,  e,  fissure  of  Sylvius  ;  1,  1,  lower  or  third  fronlal  convolution  ;  7,  7  ;  8,  8  ;  9,  9, 
three  temporal  convolutions  ;  /,  /,  and  g,  g,  parallel,  and  inferior  temporal  fissures. 

together,  especially  opposite  the  hinder  border  of  the 
frontal  lobe,  which  is  here  very  defective.  The  fissure, 
indeed,  is  so  patent,  that  without  any  separation  of  its 
margins,  a  jDortion  of  the  island  of  Reil  or  central  lobe  (C), 
though  small,  is  distinctly  visible.  This  condition  recalls 
to  mind  the  foetal  state  of  the  human  cerebrum  (fig.  128), 

*  These  are  marks  of  low  development.  In  more  liigldy  developed 
brains  the  Sylvian  fissure  is  shorter  as  well  as  more  horizontal  in 
direction. 


382  ■  THE    EXTERNAL    CONFIGURATION 

but,  so  far  as  I  am  aware,  is  not  present  in  any  adult 
quadrumanous  brain.  The  defect  in  the  frontal  lobe 
explains  the  remarkable  constricted  form  of  the  Bush- 
woman's  brain,  already  mentioned  as  existing  at  that 
point,  a  form  which  we  may  perhaps  assume  is  a  charac- 
teristic of  the  Bosjes  brain,  as  it  is  equally  present  in  the 
brain  of  the  so-called  Hottentot  Yenus,  where  it  has  also 
been  noticed  by  Gratiolet  as  a  foetal  character." 


Fig.  137.— Right  Cerebral  Hemisphere  of  a  Scotchman,  outer  aspect.  (Turner.) 
Fr,  Ft;  Frontal  lobe;  Par,  parietal  lobe;  Oc,  occipital  lobe;  T S,  temporo-sphen- 
oidal  or  temporal  lobe ;  S,  S,  Si'lviau  fissure  ;  '-S,  'S,  ascending  limb  of  Sylvian  fissm-e 
(or  'Sulcus  precentralis '  of  Ecker) ;  R,  R,  fissure  of  Rolando;  IP,  intra-parictal, 
and  P,  P,  parallel  fissures.  1,  1,  1,  Inferior,  2,  2,  2,  middle,  and  3,  3,  3,  superior 
frontal  convolutions  ;  4,  4  ascending  frontal,  and  5,  5,  ascending  parietal  convolu- 
tions ;  5',  outer  iiart  of  postero-parietal  lobule ;  (>,  G,  angular  gyrus ;  7,  7,  superior, 
8,  8,  8,  middle,  and  9,  9,  9,  inferior  temporal  convolutions;  10,  !-ui)erior,  11,  middle, 
and  12,  inferior  occipital  convolutions ;  A,  supra- marginal  lobule  ;  a,  (3,  y,  8,  first, 
second,  third,  and  fourth  annectent  or  bridging  convolutions. 

Tha  fissure  of  Bolando  (fig.  136,  d,  d)  commences  about 
1 J  inches  behind  the  tip  of  the  temporal  lobe.  "  It  ter- 
minates consideral)ly  beyond  the  middle  of  the  long  axis 
of  the  cerebrum,  nearly  as  far  back  as  the  line  of  greatest 
width  of  that  organ ;  so  that  it  passes  proportionally 
further  back  than  in  the  Hottentot  Venus,  or  indeed  than 
in  the  European." 


Chap.  XXL] 


OF    THE    HUMAN    BRAIN. 


383 


"  The  external  perpendicular  fissures  (fig.  135,  P)  can  be 
traced  as  easily  as  in  the  Hottentot  Venus  (fig.  134,  T"),  but 
are  soon  interrupted  by  the  external  connecting  convolu- 
tions {a,  /3).  Towards  the  sides  these  fissures  are  cer- 
tainly more  easily  followed  than  in  the  European — a  cir- 


FiG.  138.— Vertex  View  of  the  Brain  of  a  Scotchman.  (After  Turner.) 
Fr,  Frontal  lobe ;  Par,  parietal  lobe ;  Oc,  occipital  lobe ;  S  F,  supero-frontal, 
IF,  infer o-frontal  fissure  ;  R,  fissure  of  Rolando  ;  / P, intra-parietal,  and  P  C,  parieto- 
occipital fissure ;  S,  horizontal,  and  S',  ascending  limb  of  the  Sylvian  fissure 
A,  supra-marginal  lobule.  1,  1,  Inferior,  2,  i.',  middle,  and  3,  3,  3,  superior  frontal 
convolutions  ;  4,  4,  ascending  frontal,  and  5,  5,  pscending  pai-ietal  convolution ; 
5',  outer,  and  .5",  inner  jiart  of  postero-parietal  lobule ;  6,  6,  angular  convolution ; 
10,  tuperior  occipital  convolution,     a,  a,  first,  and  p,  second  anntctent  convolution. 


cumstance  which  imparts  a  lower  character  to  this  part  of 
the  Bosjes  brain  ;  at  the  same  time  they  are  far  more 
interrupted  than  in  the  Chimpanzee  or  Orang-outan. 
These  short  external  perpendicular  fissures  join  as  usual 
the  summits  of  the   internal  perpendicular  fissures,  and, 


184 


THE    EXTERNAL    CONFEGURATION 


together  with  the  fissures  of  Eolando,  divide  the  upper 
surface  of  the  Cerehrum  into  three  regions." 

Of  these  three  regions,  when  measured  longitudinally 
over  the  vertex,  the  parietal  is  found  to  be  specially 
defective  in  the  Bushwoman's  brain,  since  instead  of 
being  equal  to  or  rather  longer  than  the  occipital,  as  is 
commonly  the  case  in  European  brains,  it  is  very  dis- 
tinctly shorter  than  this  latter  region. 

The  parallel  Jissure  (136,/,/)  on  the  outer  surface  of  the 


Fig.  139.— Inner  Face  and  Tentorial  Surface  of  the  Left  Cerebral  Hemisphere. 
(After  Turner,) 

Fr,  Frontal  lobe ;  Par,  parietal  lobe  ;  Oc,  occipital  lobe ;  T  S,  temporal  lolje ; 
P  0,  internal,  perpendicular,  or  parieto-occipital  fissure ;  i,  i,  i,  calloso-marginal,  and 
I,  I,  calcarine  fissure  ;  m,  m,  dentate  fissure  ;  v,  n,  collateral  fissure.  17,  17,  17, 
marginal  convolution;  18,  IS,  convolution  of  corpus  callosum  ;  IS',  qinidrilateral 
lobule;  19,  19,  uncinate  convolution,  of  vvrhich  19'  is  the  'crotchet,'  or  recurved 
part ;  25,  cuneus,  or  occipital  lobule ;  9,  9,  inner  face  of  inferior  temporal  con- 
volution. 


temporal  lobe  is  "  more  tortuous  on  the  left  side  than  in 
the  Hottentot  Yenus,  though  less  so  than  in  ordinary 
European  brains." 

"  The  interval  perpevdlcitlar  fissure  (fig.  139,  PO)  is 
more  vertical  than  in  the  European,  but  much  less  so  than 
in  the  Chimpanzee — the  angle  formed  by  this  fissure  and  a 
base-line  drawn  through  the  corpus  callosum  being  in  the 
European  123°,  in  the  Bushwoman  115°,  and  in  the  Chim- 


Chap.  XXL] 


OF    THE    HUMAN    BRAIN. 


385 


panzee  93°.  As  in  the  European  brain,  however,  this 
fissure  joins  the  fissure  of  the  hippocampi  below  (fig.  139), 
whilst  in  the  Quadru- 
mana  it  usually  stops 
short  of  that  fissure." 
We  cannot  follow 
Prof.  Marshall  in  his 
interesting  and  de- 
tailed examination  of 
the  various  convolu- 
tions of  the  Bush- 
woman's  brain,  includ- 
ing his  estimation  of 
the  degree  of  their  de- 
velopment in  relation 
to  those  of  the  Hot- 
tentot Venus  and  those 
of  the  ordinary  Euro- 
pean brain ;  we  can 
only  reproduce  some 
of  his  most  interesting 
general  conclusions. 


Fig.  140.— View  of  the  Orbitii  Lobule  and  of 
the  Island  of  Reil.     (After  Turner.) 

Most  of  the  temporal  lobe  has  been  removed 
for  the  purpose  of  displaying  the  Island.  0,  Ol- 
factory sulcus  ;  T  R,  triradiate  sulcus ;  I",  pos- 
terior, 1'",  internal,  and  1"",  external  convolu- 
tions of  tlie  orbital  lobule  ;  C,  Island  of  Reil,  with 
its  radiating  convolutions  ;  1,  1,  under  surface  of 
lower  or  third  frontal  convolution  ;  4,  under 
surface  of  lower  end  of  ascending  frontal  con- 
volution ;  5,  under  surface  of  lower  end  of  parie- 
tal convolution  ;  17,  marginal  convolution. 

smaller,  and  in  all  cases 

so  mucli  less  complicated  as  to  be  far  more  easily  recognized  and 
distinguished  amongst  each  other.  This  comparative  simplicity 
of  the  Bushwoman's  brain  is,  of  course,  an  indication  of  structural 
inferiority,  and  indeed  renders  it  a  useful  aid  in  the  study  of 
the    more  complex  European    form.      On  contrasting  the  several 


All  the  primary  convo- 
lutions which  should  exist 
in  the  human  cerebrum 
"are  present  in  the  Bush- 
woman's  brain  ;  but,  as 
compared  with  the  same 
parts  in  the  ordinary 
European  brain,  they  are 


386  THE    EXTERNAL    CONFIGURATION 

regions  of  the  Cerebrum,  the  primary  convokitions  of  the  upper 
frontal  and  outer  parietal  regions  are,  on  the  whole,  the  best  de- 
veloped ;  those  of  the  middle  and  lower  frontal  regions,  the  temporal 
region,  the  central  lobes,  and  the  inner  surface  the  next ;  whilst 
those  of  the  orbital  surface  and  occipital  lobe  are  the  least  de- 
veloped." 

"  Of  the  Connecting  Convolutions,  those  highly  important  and 
significant  folds,  the  external  connecting  convolutions  are,  in  com- 
parison with  those  of  the  European  brain,  still  more  remarkably 
defective  than  the  primary  convolutions.  All  four  of  these  con- 
volutions are  present;  but  all  are  characteristically  short,  narrow, 
and  simple, instead  of  being  complex  and  occupying  a  large  space; 
hence,  though  the  external  perpendicular  fissure  is  soon  filled  up, 
the  parietal  and  occipital  lobes  are  more  easily  distinguishable  from 

one  another    than  in  the   European  brain The  numerous 

sulci  and  convolutions,  which  so  complicate  the  longer  ones  in  the 
European  brains,  are  everywhere  decidedly  less  developed  in  the 
Bushwoman — but  especially  so  in  the  occipital  and  orbital  regions, 
on  the  bent  convolution,  and  on  the  external  connecting  convolu- 
tions.    This  is  a  further  sign  of  structural  inferiority." 

Compared  with  that  of  the  Hottentot  Venus,  the  Bush- 
woman's  brain  is,  **  in  nearly  all  cases  where  comparison 
is  possible,  a  little,  though  a  very  little,  more  advanced 
and  complex  in  its  convolutional  development — the  one 
exception  being  in  regard  to  the  size  of  the  occipital  and 
external  connecting  convolutions,  which  are  smaller  in  the 
Busb woman."  But  the  resemblance  between  the  con- 
volutions of  the  two  brains  is  very  close,  whilst  the  sim- 
plicity of  their  arrangement  is  not  to  be  paralleled  or  even 
approached  in  normal  European  brains. 

It  remains  now  to  point  out  rather  more  fully  the 
nature  of  the  principal  diiicrences  presented  by  the  brains 
of  Europeans  Avhcn  contrasted  with  those  of  the  lower 
human  types  to  which  we  have  hiilu^rto  been  referring. 
This,  however,  is  a  somewhat  difficult  task,  because  wide 
individual  diU'crenccs,  relating  to  many  details  of  structure, 


Chap.  XXI.] 


OF   THE    HUMAN    BRAIN. 


387 


are  to  be  encountered  in  this  organ  in  different  Europeans. 
In  some  of  them  a  brain  is  to  be  met  with  which  appro:si- 
mates  closely  as  regards  size,  relative  development  of 
lobes,  and  complicacy  of  convolutions,  to  the  low  standard 


Fig.  ]4l.— Brain  of  Gauss,  the  Celebrated  Mathematician  and  Astronomer,  upper 
aspect.     (Sharpey,  after  R.  Wagner. ) 

I,  I,  Longitudinal  fissure ;  a,  a',  a",  upper,  middle  and  lower  frontal  convolutions  ; 
A,  A,  ascending  frontal  convolution  ;  r,  r,  fissure  of  Rolando  ;  B,  B,  ascending 
parietal  convolutions  ;  b,  b,  parietal  lobule ;  b",  supra-marginal  lobule ;  c,  c',  first 
or  upper  temporal  convolution  ;  p,  perpendicular  (or  parieto-occipital)  fissure  ; 
d,  d',  a",  upper,  middle,  and  lower  occipital  convolutions. 


afforded  by  the  brain  of  the  Bush  woman.  In  others,  the 
majority  of  characters  are  decidedly  higher,  though  in 
certain  parts  or  situations  there  may  be  presented  now  one, 
now  another,  feature  of  a  lower  type. 


All  sorts  of  grades 


888  THE    EXTERNAL    CONFIGURATION 

and  transitions  are,  in  fact,  frequently  encountered,  so 
that  the  remarks  made  in  reference  to  this  part  of  our  sub- 
ject must  be  suggestive  and  general  rather  than  precise 
and  particular. 

Looked  at  from  above,  the  shape  or  outline  of  the 
European  brain  varies  considerably.  The  narrowed  and, 
as  it  were,  compressed  anterior  lobes  in  the  Bushwoman,  as 
well  as  the  narrow  tapering  shape  of  the  occipital  lobes, 
are  eminently  foetal  characteristics.  As  a  rule,  this 
contracted  condition  of  the  anterior  lobes  is  absent  in 
the  European  brain,  and  in  some  specimens  the  shape  is 
so  broadly  oval  as  even  to  approach  the  circular  outline,  as 
in  that  of  the  Scotchman  represented  by  Turner  (fig.  138). 

The  brain  of  a  "celebrated  naturalist"  figured  by  Kudolph 
Wagner*  Iras  much  the  same  almost  circular  outline  when  seen 
from  above,  and  both  in  it  and  in  the  brain  of  the  Scotchman 
already  referred  to,  the  posterior  extremity  constitutes  the  broad 
end  of  the  oval.  On  the  other  hand  the  brain  of  the  great  mathe- 
matician and  astronomer  Gauss  (fig.  141)  has,  when  seen  from 
above,  a  distinctly  elliptical  outline— the  curve  of  the  anterior  being 
almost  exactly  equal  to  that  of  the  posterior  lobes,  and  the  greatest 
transverse  diameter  being  equidistant  from  both  extremities.  A 
similar  upper  outhne  is  to  be  seen  in  the  much  less  elaborately 
convoluted  brain  of  the  artizan  Krebs,l  although  the  side  view  of 
this  same  brain,  when  compared  with  that  of  Gauss  (loc.  cit.,  tab. 
vi.),  shows  it  to  be  very  deficient  in  depth,  both  in  the  frontal  and  in 
the  parietal  regions.  The  upper  outline  of  the  brain  of  the  philo- 
logist Hermann,  likewise  depicted  by  Wagner,  is  also  nearly  ellip- 
tical, the  posterior  being  very  slightly  narrower  than  the  anterior 
extremity.  Its  widest  transverse  diameter,  moreover,  is  situated 
midway  between  its  two  extremities,  though  this  region  corresponds 
with  the  supra-marginal  lobule  rather  than  with  the  lower  end  of 
the  ascending  parietal  convolution,  as  in  the  brain  of  Gauss  and  in 
that  of  the  artizan  Krebs.  A  reference  to  fig.  135  will  show  that 
the  brain  of  the  Bushwoman  is  also  widest  in  the  situation  of 
the  very  prominent  '  supra-marginal  lobules,'   though    these  are 

*  "  Vorstudien,"  tab.  ij.         \  Wagner,  loc.  cit.  tab.  ij.  fig.  4, 


Chap.  XXL]  OF    THE    HUMAN    BRAIN.  389 

found  to  be  distinctly  posterior  to  the  median  axis.  The  "brain  of 
the  eminent  mathematician  Dirichlet  is  longer  and  broader  than, 
either  of  the  others  tigured  by  Wagner.  Its  posterior  extremity 
is  narrower  than  the  anterior,  and  even  notably  pointed.  Its 
greatest  breadth  may  be  seen  to  be  only  slightly  posterior  to  its 
median  axis,  and  to  correspond  with  the  hinder  part  of  the  ascend- 
ing parietal  convolution. 

Notable  variations  are  therefore  to  be  met  with  in  the 
shape  of  the  Brain  as  seen  from  above,  as  might  have 
been  expected  from  a  consideration  of  the  diverse  shapes 
of  the  human  Skull  in  dilBferent  races  and  individuals.  We 


Ftg.  142.— Brain  of  Gauss,  the  Celebrated  Mathematician  and  Astronomer,  side 
view.    (Vogt,  after  R.  Wagner.) 

F,  Frontal  lobe  ;  P,  parietal  lobe ;  0,  occipital  lobe  ;  T,  temporal  lobe ;  C,  cere- 
bellum ;  Po,  pons  Varolii  ;  V  M,  medulla  oblongata  ;  S,  Sylvian  fissure  ;  R,  fissure  of 
Rolaudo;  P  >,  parallel  fissure,  a',  Upper  fold  of  frontal  convolutions  ;  a"^,  middle 
fold  of  frontal  convolutions ;  a^,  lower  fold  of  frontal  convolutions.  A,  Ascending 
frontal  (or  anterior  central)  convolution  ;  B,  ascending  parietal  (or  posterior  central) 
convolution ;  6',  b^,  b^,  upper,  middle,  and  lower  folds  of  parietal  convolutions  ; 
c',  c2,  c:',  upper,  middle,  and  lower  folds  of  temporal  convolutions;  ci',  ^2^  cj3^  upper, 
middle,  and  lower  folds  of  occipital  convolutions. 

have  extreme  '  long-heads,'  and  extreme  '  round  heads,' 
interspersed  with  multitudes  of  individuals  whose  cranial 
diameters  are  more  nearly  equal.      On  the  whole,  it  is, 


890  THE    EXTERNAL    CONFIGURATION 

perhaps,  most  frequently  found  that  the  greatest  breadth 
of  the  brain  is  behind  its  median  transverse  axis,  and  that 
its  posterior  is  more  bluntly  rounded  than  its  anterior 
extremity. 

Looked  at  from  the  side,  the  Brain  presents  certain 
obvious  differences  when  we  compare  such  simple  forms 
as  that  of  the  '  Hottentot  Yenus  '  and  the  Bush  woman,  or 
even  that  of  Krebs  the  artizan,  with  one  of  the  highly 
evolved  organs  pertaining  to  a  man  of  great  and  subtle 
intellect,  such  as  Gauss. 

One  of  the  most  notable  characteristics  of  the  Brain 
of  Gauss  is  to  be  found  in  the  great  development  of  the 
Frontal  Lobes.  This  is  rendered  evident  by  the  fact  of 
their  comparative  length,  breadth  and  height,  and  also  by 
reason  of  the  extreme  complicacy  of  their  three  tiers  of 
convolutions  (fig.  142,  a\  a^,  a^).  Wagner  gives  a  full-size 
representation  of  these  lobes,  viewed  from  the  front,  and 
also,  for  comparison,  a  similar  view  of  the  frontal  lobes  of 
the  artizan  Krebs.  The  difference  between  them  is  very 
marked. 

The  writer  has  in  his  possession  the  brain  of  another 
celebrated  mathematician,  the  late  Professor  De  Morgan, 
and  although  in  it  the  frontal  lobes  are  likewise  large  and 
well  developed,  their  convolutions  are  by  no  means  so  intri- 
cate as  in  that  of  Gauss.  But  in  the  brain  of  a  Journalist 
(formerly  a  Clergyman)  who  died  some  years  ago  in 
University  College  Hospital,  the  size  of  the  frontal  lobes 
is  distinctly  greater,  and  the  intricacy  of  their  convolutions 
altogether  remarkable — fully  equalling,  even  if  it  does 
not  exceed,  that  met  with  in  the  brain  of  Gauss.  In  other 
regions  also  this  brain,  of  an  educated  though  not  distin- 
guished man,  is  rather  more  highly  convoluted  than  that 
of  T)e  Morgan,  as  it  is  also  distinctly  heavier.  It  was 
preserved,  indeed,  both  because  it  was  the  brain  of  a  well- 


Chap.  XXL] 


OF    THE    HUMAN    BRAIN. 


391 


educated  person  and  because  it  presented  a  well-marked 
complicacy  of  its  convolutions,  with  the  view  of  subse- 
quently comparing  it  with  that  of  the  recently-deceased 
Mathematician. 

In  both  these  brains,  as  well  as  in  that  of  Gauss,  the 
fissures  of  Kolando  are  very  sinuous,  owing  to  the  exist- 
ence of  many  secondary  foldings  of  the  ascending  frontal 
and  parietal  convolutions.*     The  relative  position  o^  these 


Fig.  143. — Front  view  of  Frontal  Lobes  of  the  Brain  of  a  Journalist,  showing  the 
extreme  complicacy  of  its  Convolutions.  Owing  to  slight  obliquity  of  position, 
the  right  Frontal  Lobe  is  more  fully  shown  than  the  left.  (Accurately  drawn  by 
v.  Horsley,  from  a  photograph. ) 

fissures  was,  however,  very  different  in  the  two  brains, 
and  in  that  of  the  Journalist  the  distance  of  the  lower 
end  of  the  fissure  of  Rolando  from  the  tip  of  the  temporal 
lobe  was  altogether  remarkable. 

As  a  consequence  apparently  of  a  blindness  of  the 
right  eye,  dating  from  a  few  days  after  birth,  the  left 
Cerebral   Hemisphere  of  De   Morgan's   brain  was  notably 

*  ISTo  bridge-like  convolution  was  to  be  seen  crossing  tbe  fissure 
of  Eolando  in  either  brain.  On  the  right  side,  but  not  on  the  left, 
and  this  only  in  the  brain  of  De  Morgan,  the  fissure  of  Eolando 
opened  into  the  fissure  of  Sylvius. 


392  THE    EXTERNAL    CONFIGURATION 

smaller  than  the  right,  though  the  measurements  of  the 
organ,  now  that  it  has  become  flattened  from  its  own  weight, 
and  is  slightly  shrunk  in  consequence  of  its  preservation 
in  spirits,  do  not  show  this  so  clearly  as  when  it  was  in 
the  fresh  condition.*  Still  even  now  the  left  hemisphere 
is  distinctly  smaller  than  the  right,  both  in  length  and 
in  breadth.  The  occipital  lobes  are  as  nearly  equal  in 
length  as  they  can  be,  but  the  left  internal  perpendicular 
fissure  (owing  to  the  smaller  size  of  the  frontal  and 
parietal  lobes)  now  lies  exactly  f  in.  in  front  of  that  of  the 
right  hemisphere.  The  left  occipital  lobe  is,  moreover, 
distinctly  narrower  and  less  rounded  externally  than  that 
of  the  right  side.  The  temporal  lobes  are  of  equal 
length,  but  in  regard  to  relative  breadth  they  have  been 
too  much  altered   by  pressure  to  enable  any  opinion  to  be 

*  This  brain  was  removed  on  the  third  day  after  death,  and  was 
not  in  a  good  condition  for  preservation.  The  measurements  over 
the  vertex,  then  taken  with  great  care  by  means  of  a  narrow  tape, 
were  as  follows  : — 

Anterior  extremity  of  Upiocr  end  of  Fissure  of  Upper  end  of  Perpendi- 
Frontal  Lobe  to  upper  end  Kolaudo  to  upper  end  of  cular  Fissure  to  posterior 
of  Fissure  of  ilolando.  Perpendicular  Fissure.  extremity  of  Occipital  Lobd. 

Inches. 

2| 

Besides  the  sj)ecial  arrest  of  development  met  with  in  the  left 
hemisphere,  the  brain  generally  was  distinctly  shrunken,  partly  from 
the  eti'ect  of  age,  and  partly  from  disease  which  had  produced  groat 
and  general  emaciation  during  the  last  twelve  montlis  of  life.  Prof. 
De  Morgan  was  well  known  to  have  had  an  exceptionally  large  head, 
so  that  had  it  not  been  for  age  and  the  wasting  above-mentioned  his 
brain  would  probiibly  have  weighed  much  more  than  it  did,  viz., 
52foz.  The  writer  found  the  measurements  of  Prof.  De  Morgan's 
head  (almost  free  from  hair)  to  be  as  follows  : — Circumference, 
24^  in. ;  longitudinal  measurement  over  vertex  (root  of  nose  to  occi- 
pital protuberance),  15§  in.;  transverse  measurement  over  vertex 
(from  external  auditory  meatus  to  its  fellow  of  opposite  side),  15giu. 


Inches. 

Inches. 

L. 

41 

2f 

R. 

5§ 

n 

Chap.  XXL]  OF    THE    HUMAN    BRAIN.  393 

formed.  The  diminution  in  genenil  size  of  the  frontal 
and  parietal  lobes  is  still  very  obvious,  both  in  breadth  as 
well  as  in  iength ;  though  it  is  not  a  diminution  localized 
in  any  particular  parts  of  these  lobes.  Nor  is  there  any 
appreciable  difference  observable  in  the  convolutional  de- 
velopment of  any  part  of  the  hemisphere,  as  compared 
with  that  of  the  opposite  side.  The  region  of  the  '  supra- 
marginal  lobule  '  and  of  the  '  angular  gyrus  '  seems  cer- 
tainly to  be  just  as  well  developed  on  the  left  as  it  is 
on  the  right  side,  though  these  are  the  convolutions  which, 
according  to  Ferrier,  are  to  be  regarded  as  the  principal 
site  of  the  '  Visual  Centre.' 

Except  for  the  degenerated  condition  and  wasted 
appearance  of  the  right  optic  nerve  and  the  correspondin,'^ 
left  'optic  tract,'  there  is  nothing  to  be  discovered  which  caj 
possibly  account  for  the  smaller  size  and  stunted  develop- 
ment of  the  left  Hemisphere.  The  anterior  of  the  quadri- 
geminal  bodies  on  the  left  side  is  slightly  less  prominent 
than  that  of  the  right  side,  and  it  is  also  slightly  different 
in  colour  :  but  it  was  not  examined  previous  to  the  immer- 
sion of  the  Brain  in  spirits  of  wine.  The  Cerebellum  seems 
to  be  quite  symmetrical ;  its  right  and  left  halves  present- 
ing the  same  measurements.  And,  in  regard  to  this 
point,  it  is  important  to  observe  here  that  Prof.  De  Mor- 
gan had  never  suffered  from  any  paralytic  condition  or 
affection  of  motihty,  so  that  my  first  impression  that  there 
ought  to  have  been  an  associated  atrophy  of  the  opposite 
lateral  lobe  of  the  Cerebellum  (as  in  many  cases  of  atrophy 
of  one  Cerebral  Hemisphere)  was  seen,  on  further  con- 
sideration, not  to  be  well-grounded.  We  may  rightfully  look 
for  this  in  instances  of  atrophy  of  one  Cerebral  Hemisphere 
associated  with  unilateral  motor  Paralysis,  but  not  in  cases 
where  the  latter  condition  is  absent,  and  in  which  one 
of  the  Hemispheres   seems  to  be  imperfectly   developed 


894  THE    EXTERNAL    CONFIGURATION 

merely  from  the  fact  of  its  having  lacked  the  stimuli 
which  ought  to  have  come  to  it  through  an  all-important 
sense  like  that  of  Sight.  This  is  a  distinction  important 
to  be  borne  in  mind. 

Some  measurements  have  been  made  of  this  veiy  un- 
symmetrical  Brain  of  the  celebrated  Mathematician  (whose 
mental  powers  were  so  great  notwithstanding  the  inequality 
of  its  Hemispheres),  and  they  have  been  placed  side  by 
side  with  figures  obtained  from  other  similar  measurements 
of  the  well-evolved  brain  of  the  educated  but  comparatively 
obscure  Journalist.  The  weight  of  this  latter  brain  was 
56oz.,  so  that  it  would  have  taken' a  high  place  if  it  had 
been  incorporated  with  the  table  on  p.  370.  It  will  be  ob- 
served that  the  left,  as  is  frequently  the  case  (see  fig.  135), 
is  slightly  but  distinctly  longer  than  the  right  Hemisphere. 

Comparative  Measurements  of  Two  Brains. 

Anterior  extremity  of  Upper  end  of  Fissure  of  Upper  end  of  Perpen- 
Frontal  Lobe  to  upper  end  of  Rolando  to  upper  end  of  dicular  Fi.'sure  to  pos- 
Fissure  of  Rolando.  Perpendicular  Fissure.  terior  extremity  of  Occipi- 

tal Lobe. 
Inches.  Inches.  Inches. 


De  Morgan 


|r.   5 

i 


^H 


2 


L.   5«  2J  2| 


Journalist    ^  -d     j-a                            02  O-^ 

Tip  of  Temporal  Lobe        Lower    end    of  Tip  of  Temporal  Fnd    of    Fisaiire 

to  lower  end  of  Fissure    Fissure  of  Kolando    Lobe  to  end  or  Fis-  of  Sylvius  to  upper 

of  Uulando.                         to   upnor    end    of  sure  of  Sylvius.  end    of     I'erpondi- 

Fissuie  of  Sylvius.  cular  Fissure. 

Inches.                Inches.  Inches.  Inches. 

1 1  9i'>-  .Si 

^  8  "8  •^S 


Do  Morgan  j  t?   91. 

Journalist    i  xj   o^  7  q 


1  3J 


r>7 


Another  notable  difference  often  met  with  in  European 
brains  of  higher  type,  serving  to  separate  them  from  such 
organs  as  that  of  the   Hottentot  Venus    (fig.    133),  lies 


Chap.  XXL]  OF    THE    HUMAN    BRAIN.  895 

in  the  shortness  of  the  Sylvian  Fissure.  It  may 
scarcely   reach  half  way   back  to  the  upper  end  of  the 

*  perpendicular  fissure,'  and  may  be  separated  therefrom 
by  several  convolutions  instead  of  only  by  the  descending 
limb  of  the  '  angular  gyrus,'  as  is  the  case  in  the  Chim- 
panzee ;   or  by  this  convolution  together  with  the  upper 

*  bridging  convolution,'  as  in  the  two  South  African 
women. 

The  Sylvian  Fissure  is  most  elongated  in  some  of  the  Quadru- 
mana  such  as  the  Howler  (p.  291),  and  also  in  the  brains  of  the 
Saimiri  depicted  by  Gratiolet,*  in  each  of  which  it  extends  back 
almost  to  the  '  great  longitudinal  fissure.'  It  is  only  slightly  less 
elongated  in  the  Squirrel  Monkey,  the  Macaque  and  other  allied 
forms  (figs.  105, 106) ;  and  is  similarly  long  even  in  the  Chimpan- 
zee.f  It  has  been  already  pointed  out  (p.  345)  that  the  length  of 
the  Temporal  Lobe,  and  the  extent  of  the  posterior  prolongation 
of  the  fissure  of  Sylvius,  are  also  notable  characteristics  of  the 
human  foetal  brain.  This  feature  is  well  shown  in  Gratiolet's  figure 
of  the  brain  of  a  foetus  of  about  6^  months.  J 

This  Simian  and  foetal  characteristic  of  the  organ  reveals  itself 
also  even  in  the  adult  condition  of  some  of  the  lower  types  of  the 
Human  Brain.  It  is  seen,  for  instance,  in  the  Hottentot  Venus  (fig. 
133)  and  to  a  less  extent  in  the  Bushwoman  (fig.  136) ;  also  in  the 
brain  of  the  criminal  Fieschi  (of  '  infernal  machine '  notoriety) 
as  depicted  by  Gratiolet,§  and  in  that  of  the  artizanKrebs  as  repre- 
sented by  Wagner. II  In  Leuret  and  Gratiolet's  figure  of  the  brain  of 
a  '  Charruas  '  (PI-  xix.  fig.  1),  however,  though  it  presents  in  other 
respects  many  infantile  characters,  we  find  the  fissure  of  Sylvius 
very  short,  just  as  it  exists  in  some  of  the  best  developed  human 
brains,  e.g.  that  of  Gauss,  and  still  more  notably  in  that  of  De 
Morgan,  as  well  as  in  the  Journalist  above  referred  to.  In  both  of 
these  latter  brains  more  than  one-half  of  the  Sylvian  Fissure,  aa 
it  exists  in  some  of  the  Qaadrumana,  has  bean  obliterated — since 

*  "  Anat.  Comp.  du  Syst.  Nerv.,"  PI.  xxix.  figs.  11  and  12. 

f  Gratiolet,  loc.  cit.  PI.  xxiv.  fig.  6. 

+  Idem.  PI.  XXX.  fig.  2. 

§  PI.  xxij.  fig.  2. 

II  "  Yorstudien,"  tab.  vi.  fig.  2. 


896  THE    EXTERNAL    CONFIGURATION 

the  measurements  of  these  brains  from  the  upper  end  of  the 
'  perpendicular  Fissure  '  across  the  parietal  lobe  to  the  posterior 
extremity  of  the  Sylvian  Fissure,  are  just  equal  to  the  measure- 
ments from  the  latter  point  even  as  far  as  the  tip  of  the  correspond- 
ing Temporal  Lobe. 

This  progressive  shortening  of  the  Sylvian  Fissure  appears  not 
to  have  been  distinctly  pointed  out  before.  Yet  it  would  seem 
to  be  a  change  of  precisely  the  same  order  as  -that  which  leads  to 
the  progressive  obliteration  of  the  '  external  perpendicular  Fis- 
sure,' to  which  much  attention  has  been  given  by  anatomists. 

The  above-mentioned  shortness  of  the  Sylvian  Fissure 
in  the  more  highly  evolved  brains  tends  to  confer  a 
corresponding  shortness  upon  the  Temporal  Lobe.  The 
proportional  breadth  of  this  segment  of  the  brain  is  also 
decidedly  diminished  in  the  brain  of  Gauss.  The  broad 
simple  convolutions  of  the  Temporal  Lobe  in  the  Hotten- 
tot Venus  (fig.  133)  contrast  notably  with  the  much  more 
complex  corresponding  gyri  in  the  brains  of  the  two 
Mathematicians  as  well  as  in  that  of  the  Journalist.* 

The  Occipital  Lobe  has  a  much  greater  depth  in  the 
brains  of  Gauss,  De  Morgan  and  of  the  Journalist,  than 
is  to  be  met  with  in  the  lower  human  types  previously 
described.  Consequently  in  them  the  inferior-posterior 
border  of  the  Cerebral  Hemisphere,  as  it  extends  along 
the  side  of  the  Cerebellum,  is  much  more  nearly  horizon- 
tal than  it  is  in  either  of  the  two  African  women.  In 
these  latter,  however,  an  advance  of  the  same  kind  is  to 
be  met  with  in  comparison  with  what  obtains  in  the  Cere- 
bral Hemispheres  of  the  great  '  man-like'  Apes  (p.  296). 

*  In  the  brain  of  the  61  month  Foetus,  and  in  that  of  Fieschi 
represented  by  Gratiolet  (loc.  cit.,  PI.  xxx.  tig.  2,  and  PI.  xij.  fig.  2) 
the  Temporal  Lobes  are  both  long  and  broad,  whilst  in  that  of  the 
new-born  Infant  (PI.  xxx.  fig.  3),  and  in  the  brain  of  the  '  Charruas* 
(PI.  xix.  fig.  1),  this  same  Lobe  though  short  is  still  extremely 
broad. 


Chap.  XXL] 


OF    THE    HUMAN    BRAIN. 


397 


In  the  liigber  forms  of  the  Haman  Brain — as  in  those  of 
Gauss  and  De  Morgan,  and  also  in  the  Journalist — the 
Temporal  and  Occipital  Lobes  of  each  Hemisphere  together 
bear   a    mach   smaller  proportion   to  the  mass   of  brain- 


\^l^ii!]^0llt^ 


Fig.  144.— Under  Surface  of  the  Human  Brain.  (Allen  Thomson.) 
1,  1,  Great  longitudinal  fissure  ;  2,  2',  2",  convolutions  of  under  surface  of  frontal 
lobe ;  3,  3,  3,  prolongation  to  base  of  the  fissure  of  Sylvius ;  4,  4',  4",  convolutions 
of  the  temporal  lobe  ;  5,  5',  occ'pital  lobe  ;  6,  anterior  pyramids  of  medulla  ;  +,  pos- 
terior extremity  of  median  lobe  of  cerebellum  ;  7,  8,  9,  10,  lobules  of  the  lateral  lobe 
of  the  cei  ebelinm.  I-IX.  Cranial  nerves,  all  but  the  first  more  fully  Feen  in  next 
figure.  The  ninth  nerve  of  the  right  side  has  been  removed.  X.  First  cervical 
nerve. 


substance   comprised  in  the   Frontal   and  Parietal  Lobes 
than  is  the  case  in  brains  of  a  lower  type.     In  the  lower 
Quadrumana,  also,  the  Tempore- Occipital  segment  of  the 
18 


398 


THE    EXTERNAL    CONFIGURATION 


Hemisphere,  instead  of  being  much  less,  is  about  equal  to, 
or  it  may  be  of  even  slightly  greater  bulk  than,  the  con- 
joined Fronto- Parietal  segment.  Thus  the  proportions 
met  with  in  the  lower  human  types  are,  as  it  were,  in- 
termediate between  those 
which  obtain  in  the  higher 
human  types  on  the  one 
hand  and  in  the  Quadru- 
mana  on  the   other. 

The  diminution  in  size 
of  the  Tempore- Occipital 
segment  in  the  brain  of 
human  beings  generally,  is 
perhaps  more  apparent  than 
real.  The  very  great  in- 
crease in  the  size  of  the 
Frontal  and  of  the  Parietal 
regions  is,  at  least  in  part, 
another  means  of  accounting 
for  the  altered  proportion. 
It  is  certain,  indeed,  that 
the  convolutions  of  the  Tem- 
poral Lobes  tend  to  become 
more  complex  in  higher 
human  brains,  and  it  is 
equally  certain  that  there 
is  also  a  tendency  to  an 
actual  increase  in  the  size 
of  the  Occipital  Lobes.  In 
the  more  highly  evolved 
brains  these  Lobes  become 
deeper  and  also  fuller  and 
more  rounded.  There  is,  moreover,  a  notable  increase  in 
the  complexity  of  the  Occipital  Convolutions. 


Fig.  145.— Undet  buif.i  c  of  Ctrel>ral 
Peduncle,  Pons,  and  Medulla,  showing 
Connections  of  the  Cranial  Nerves.  (Sap- 
pey,  after  Hirsclifeld.) 

1,  Infundibiilum  of  pituitary  body ; 
2,  part  of  floor  of  third  ventricle  ;  3,  cor- 
pora mamillaria;  4,  cerebral  peduncles; 
5,  j)ons  ;  C,  optic  nerves,  crossiug-  in  the 
middle  line  so  as  to  form  the  ehiasma  ; 

7,  common    motor    nerves    of    e.\eball; 

8,  nerviis  patheticus ;  9,  trigeminus ; 
10,  external  ocular  nerve  ;  11,  facial  nerve; 
12,  auditory  nerve ;  13,  nerve  of  Wrisberg  ; 
14,  glossopharyngeal  nerve;  15,  A'agus  or 
pneimiogastric  ;  16,  spinal  accessory  ; 
17,  hypoghssal  nerve  (cut  av^^ay  on  one 
side). 


Chap.  XXL] 


OF    THE    HUMAN    BHAIN. 


399 


The  latter  is  a  point  of  considerable  importance,  and 
not  alwa^'s  sufficiently  borne  in  mind  by  those  who  have 
dwelt  upon  the  large  size  of  the  Occipital  Lobes  in 
many  of  the  Quadrumana.  If  these  parts  seem  to  be 
relatively  smaller  in  Man,  it  must  not  be  forgotten  that  in 
Monkeys  and  in  Apes  their  surfaces  are  smooth  and  com- 
paratively unconvoluted,  whilst  in  Man,  in  proportion  to 
their  size,  the  area  of  superficial  grey  matter  on  the  Occipital 
Lobes  becomes  en- 
ormously increased 
by  reason  of  the 
number  and  depth 
of  their  sarface-fold- 


mgs. 

Thus  we  find  in 
the  Brain  of  Man 
not  so  much  new 
parts  or  regions,  as 
an  enormous  deve- 
lopment of  pre- 
existing parts  and 
regions.  Again,  the 
degree  of  such  in- 
creased development 
is  by  no  means 
everywhere  the  same. 
These  are  both  of  them  facts  of  great  significance  from  a 
psychological  point  of  view — and  especially  from  the 
point  of  view  of  that  Psychology  which  has  its  roots 
in  the  general  Philosophy  of  Evolution. 


Fig.  146.— Section  through  the  left  Occipital  Lobe 
of  a  Human  Bi-ain  ;  showing  the  number  and  depth 
of  its  surface-foldings. 


One  of  the  most  notable  peculiarities  of  the  Human 
Cerebrum  is  that,  in  various  ways,  its  two  Hemispheres  are 
not  quite  symmetrically  developed. 


400  THE    EXTERNAL    CONFIGURATION 

(1.)  Though  the  situation  of  the  *  primary  *  Fissures 
is  subject  to  little  variation  in  the  two  Hemispheres, 
still  in  the  more  highly  convoluted  Brains  many  of  the 
separate  Convolutions  are  apt  to  present  differences  in  the 
number  and  arrangement  of  their  minor  folds  or  indenta- 
tions. Hence  slight  differences  in  the  appearance  of 
corresponding  Convolutions  on  the  two  sides  of  the  brain 
are  occasionally  to  be  met  with ;  although  in  different 
individuals  the  regions  in  which  dissimilarity  is  most 
marked  are  by  no  means  necessarily  the  same,  nor  is 
the  greatest  complexity  always  to  be  found  on  the  same 
Hemisphere  in  these  different  regions. 

Much  more  has  yet  to  be  learned  in  regard  to  these 
points,  but  the  broad  conclusion  is  thoroughly  warranted 
that  this  asymmetrical  development  of  the  convolutions  is 
only  a  little  more  marked  in  the  lower  Human  Races  than 
it  is  amongst  the  higher  Apes,  and  that  it  becomes  dis- 
tinctly most  marked  in  the  more  highly  convoluted  brains 
pertaining  to  representatives  of  the  higher  or  more 
civilized  Human  Races. 

(2.)  It  has  been  noted  by  various  anatomists  that  the 
left  Hemisphere  is  very  frequently  slightly  longer  than  its 
fellow,  so  that  the  tip  of  the  left  Occipital  Lobe  is  apt  to 
project  distinctly  behind  that  of  the  right  side. 

(3.)  The  writer  noticed  about  fifteen  years  ago  that  a 
distinct  difference  in  the  shape  of  the  tips  of  the  Occipi- 
tal Lobes  frequently  exists* — that  of  the  left  side  being 
generally  tapering  and  rudely  conical,  whilst  the  right  is 
often  rather  flattened  at  the  end  and  has  at  its  inner  border 
a  groove-like  depression  about  ^ih  of  an  inch  in  diameter 
(fig.  14.7).  The  direction  of  the  groove  from  below  up- 
wards, is  also  inwards  and  forwards. 

*  And  sul>sequently  called  attention  to  it  in  "  Trans,  of  Patholog. 
Soc,"  18(31>,  vol.  .\Y.  p.  4. 


Chap.  XXI.] 


OF    THE    HUMAN    BRAIN. 


401 


In  a  large  proportion  of  brains,  and,  as  it  would  seem, 
especially  in  those  of  Women,  this  conformation  of  the 
right  Occipital  Lobe  exists  to  a  well-marked  extent.  In 
others,  it  is  only  slightly  marked  ;  whilst  on  rare  occasions 
a  more  or  less  obvious  groove  exists  on  each  side.  In  a 
still  smaller  number  of  cases  a  groove  is  met  with  at 
the  tip  of  the  left  instead  of  the  right  Occipital  Lobe,  or 
it  may  be  absent  on  both  sides.* 

The  Occipital  Convolutions  in  the  situation  of  the 
groove  are  distinctly  depressed,  but  no  projection  from  the 
inner  surface  of  the  skull  or  thickening  of  the  membranes 
has  ever  been  met  with  which  could  account  for  its  forma- 
tion. Of  late  the  writer  has  adopted  the  view  that  this 
*  occipital  groove  '  is  due  to  the  pressure  exerted  by  the 
posterior  extremity  of  the  longitudinal  sinus  and  the  right 
side  of  the  '  torcular  Herophili '  or  meeting-point  of  the 
venous  sinuses  (fig.  148).  Why  the  pressure  should  be  more 

*  In  thirty-five  consecutive  post-mortem  examinations  the  con- 
dition of  the  Occipital  Lobes  has  been  noted,  partly  by  myself  and 
partly  by  Mr.  J.  T.  Gadsby  or  Mr.  0.  E.  Beevor — my  late  able 
•assistants'  at  University  College  Hospital — with  the  view  of 
ascertaining  the  relative  frequency  of  these  different  conditions. 
The  results  are  embodied  in  the  following  Tables: — 


Side. 


Table  I. 


Sex. 


Total. 


M. 

•  F. 

Eight  .    . 

15 

13 

28 

Left.     .     . 

1 

1 

2 

Both  Sides 

3 

1 

4 

Absent .     . 

1 

0 

1 

20    15 


35 


Table  II. 


Degree. 

3  . 

2  . 

1  . 

0  . 


Sex. 


M. 
1 

8 

10 
1 


20      lb 


In  Table  II.  under  '  Degree,'  the  figure  3  signifies  that  tho 
j-roove  was  '  very  well  marked  ';  2,  that  it  was  '  moderately  well 
marked  ' ;  and  1,  that  it  was  only  *  slightly  marked.' 


402 


THE    EXTERNAL    CONEIGURATION 


on  the  right  side  than  on  the  left  is  by  no  means  clear. 
It  might  perhaps  be  occasioned  by  the  slightly  increased 
length  of  the  left  Hemisphere,  pressing  backwards  against 
the  left  side  of  the  '  torcular,'  and  so  diverting  a  larger 
current  of  the  blood  flowing  along  the  longitudinal  sinus 
towards  the  right.  It  has  been  long  known,  indeed,  that 
the  groove  in  the  occipital  bone  for  the  right  '  lateral  sinus ' 
is  often  distinctly  broader  than  that  for  the  left  sinus, ^ — 


Fig.  147.— View  of  Occipital  Lobes  and  of  Cerebellum  from  behind,  showing  the 
*  Occipital  Groove '  at  the  tip  of  the  righr.  Hemisphere.  (From  a  drawing  by 
V.  Ilorslcy.)  1,  The  Groove:  2,  2,  External  Perpendicular  Fissure.  c,  c,  The 
Cerebellum. 

» 

thus  conclusively  showing  that  in  all  such  cases,  at  least, 
the  larger  blood  current  is  accustomed  to  pass  away  from 
the  cranium  along  this  side. 

(4.)  The  left  Hemisphere  was  said  by  Dr.  Boyd  to  be 
generally  heavier  than  the  right  by  nearly  half  an  ounce. 
This,  however,  has  been  questioned  by  some  investigators, 

*  See  fig.  23  of  Gray's  "  Anatomy  "  (3rd.  Edn.),  where  this 
condition  is  well  represented. 


CnAK  XXI.' 


OF    THE    HUMAN    BRAIN. 


403 


and  actually  denied   by  others  to  be   a  usual  condition. 

Some  of  the  latter  even  affirm  that  though  a   difference 

often  exists,  the  superiority  in  weight  is  most  commonly  in 

favour  of  the  right  rather  than  the  left  Hemisphere.    This 

point  cannot,  perhaps,  be  definitely  decided  for  the  present. 

It  is  obvious  that  very  great  care  is  needed  in  making 

the  sections  through  the  ^ 

'  cerebral       peduncles ' 

and  '  corpus  callosum,' 

preparatory      to      such 

comparative    weighings 

of    the     two     Cerebral 

Hemispheres,  and  also 

that      the      weighings 

themselves  require  to  be 

made  with  the  greatest 

care. 

(5.)  The  writer  many 
years  ago  ascertained 
that  the  specific  gravity 
of  the  Grey  Matter 
from  the  frontal  parietal 
and  occipital  Convolu- 
tions, respectively,  is  ^jg^  14s.— Posterior  Diagrammatic  View  of 
often  slio'htlv  hi""her  on  ^ura  Mater  with  Great  V^enousSimises.  (Todd.) 
'-'  The  posterior  portion  of  the  Cranium  and  the 

the  left  than  it  is  on 
the  right  Hemisphere, 
though  such  superior 
density  does  not  neces- 
sarily exist  in  each  of  these  regions  in  t]ie  same  indivi- 
dual.* This  unexpected  result  frequently,  though  not 
invariably,  showed  itself,  even  where  every  care  was  taken 
to  get  rid  of  sources  of  fallacy.  Further  observations  are, 
*  See  "  Journal  of  Mental  Science,"  January,  1866,  p.  493. 


IJosterior  arches  of  the  upper  spinal  Vertebrae  are 
svipposed  to  be  removed,  s,  The  longitudinal 
sinus  ;  t,  the  'torcular  Herophili,'  where  longi- 
tudinal and  occipital  sinuses  meet,  and  whence 
the  lateral  sinuses  (e)  diverge. 


404  THE    EXTERNAL    CONFIGURATION 

however,  also  needed  in  regard  to  this  subject,  and  other 
convokitions  than  those  above  named  should  be  similarly 
tested.* 


The  Cerebellum  and  its  Lobes. 

The  Cerebehum  or  '  little  Brain,'  in  the  erect  posi- 
tion of  the  body,  is  situated  behind  and  above  the  '  pons ' 
and  Medulla  (fig.  132),  and  lies  in  a  posterior  hollow  of  the 
skull  beneath  the  Occipital  Lobes,  from  which  it  is  sepa- 
rated merely  by  a  membranous  partition.  This  membrane, 
named  the  '  tentorium,'  is  an  internal  horizontal  prolonga- 
tion from  the  '  dura  mater ; '  the  Occipital  Lobes  lie  on  it 
above,  while  the  uj)per  surface  of  the  Cerebellum  is  in 
contact  with  it  below. 

The  relative  weight  of  the  Cerebellum  as  compared 
with  the  Cerebrum  has  already  been  referred  to,  and  also 
the  fact  of  the  great  and  progressive  develo]^ment  of  the 

*  lateral    lobes  '    of   this  organ  in  the   Quadrumana,  and 
even  more  markedly  in  Man,  as  compared  with  that  of  the 

*  middle  lobe  ' — which  in  him  becomes  a  relatively  diminu- 
tive structure. 

No  detailed  reference  to  the  relative  development  of 
the  several  parts  of  the  Cerebellum  will  here  be  made, 
though  the  names  of  these  parts  may  be  ascertained  by 
the  reader  who  will  carefully  study  figs.  149  and  150,  and 
the  references  thereto.  The  comparative  study  of  the 
parts  of  the  Cerebellum  has  not,  indeed,  received  that 
amount  of  attention  from  workers  generally  which  has 
been  bestowed  upon  the   Cerebrum  ;  and  even  if  it  had 

*  An  increased  number  of  '  intercellular  processes  '  and  fine '  com- 
missural fibres '  within  the  Grey  Matter  (making  this  matter  ap- 
proximate more  in  character  to  the  denser  *  white  substance ')  mignt 
be  causes  of  such  slightly  increased  specific  gravity. 


Chap.  XX[.] 


OF   /THE    HUMAN    BRAIN. 


405 


been  otherwise,  the  altogether  subordinate  importance 
of  this  organ  in  regard  to  Mind  would  quite  justify  us  in 
dealing  much  more  briefly  with  its  external  anatomy.* 

The  whole  external  surface  of  the  Cerebellum  is  scored 
by  a  very  large  number  of  '  fissures/  some  of  which  are 


Fig.  149.— Upper  Surface  of  the  Cerebellum.  (Sappey,  after  HirscMeld.)  1,  1, 
Fuperior  '  vermiform  process '  (middle  lobe)  wliose  anterior  extremity  bas  been  pushed 
backwards  in  order  to  show  the  Corpora  Quadrigemina  ;  2,  posterior  extremity  of 
the  superior  and  inferior  '  vermiform  processes,' and  of  the  median  fissure  of  the 
Cerebellum  ;  3,  great  circumferential  fissure ;  4,  great  fissure  of  the  upper  surface 
which  divides  it  into  two  principal  segments  ;  5,  posterior  of  these  segments  in  the 
form  of  a  crescent ;  6,  6,  G,  6,  6,  anterior  segment,  quadrilateral,  and  composed  of 
five  secondary  curved  segments  like  the  preceding — each  of  these  segments  being 
composed  of  closely  packed  'laminai'  of  different  sizes,  separated  by  fissures  of 
varying  depths  ;  7,  7,  sections  of  the  Cerebral  Peduncles;  8,  '  posterior  commissure' 
of  the  Cerebrum  ;  9,  Corpora  Quadrigemina. 

much  deeper  than  others.  These  deeper  fissures  are 
comparatively  few  in  number,  and  they  constitute  the 
boundaries  of  the  several  '  lobes '  and  '  lobules  '  of  this 
organ.  Between  them  are  others  more  or  less  concentri- 
cally  arranged,  which  vary   much    in   length   and  depth. 

*  A  very  elaborate  work  on  the  CerebeUum  ('"  Ban  cles  kleinen 
Gehirus),"  richly  illustrated,  has  been  issued  by  StilHng. 


406 


THE    EXTERNAL    CONFIGURATION 


The  number  of  these  fissures  of  the  second  order  has 
been  computed  to  be  from  600  to  800.  They  divide  the 
surface  of  the  Cerebellum  into  a  multitude  of  '  laminae,' 
the  nature  and  arrangement  of  which  will  be  better  ap- 
preciated after  an  examination  of  figs.  156,  162,  166. 


Fig.  150.— Inferior  Surface  of  the  Cerebellum  (Sappey,  after  Hirschfeld. )  1,1, 
Inferior  vermiform  process  ;  2,  2,  median  fissure  of  the  cerebellum  ;  3,  3,  3,  lobes 
and  lobules  of  the  cerebellar  hemispheres;  4,  'amygdala'  or  almond-like  lobe ; 
6,  lobule  of  the  pneumogastric ;  6,  pons  Varolii;  7,  median  groove  on  the  same; 
8,  middle  peduncle  of  the  cerebellum  ;  9.  cut  surface  of  medulla  ;  10,  anterior 
extremity  of  the  great  circumferential  fissiu-e  ;  11,  anterior  border  of  the  upper 
surface  of  the  cerebellum  ;  12,  motor  root  of  the  trigeminal  nerve  ;  13,  sensory  root 
of  the  same  ;  14,  nerve  of  the  external  ocular  muscle  ;  15,  facial  nerve  ;  10,  nerve  of 
Wrisberg;  17,  auditory  nerve;  18,  glosso-pharyngeal  nerve;  19,  pneumogastric 
nerve  \  20,  si)inal  accessory  nerve  ;  21,  hj'poglossal  nerve. 

According  to  Marshall,  the  Cerebellum  of  the  Bush- 
woman  was  more  prominent  at  the  sides,  and  proportion- 
ally wider  and  longer  than  in  the  European,  though  its 
outline  was  not  so  fall  and  rounded,  and  its  actual  bulk 
was  less.  As  the  result  of  laborious  comparative  investi- 
gations, he  says,  "  tlie  number  of  lamime  in  the  Bush- 
woman's  Cerebellum  agrees  very  closely  with  that  in  the 
European,  the   dilferences  being  probably  only   such   as 


CiiAP.  XXL]  0¥    THE    HUMAN    BRAIN.  407 

might  be  met  with  between  individuals  of  either  race." 
The  relative  number  in  the  several  parts  was,  however, 
found  to  be  different  in  some  of  the  smaller  lobes,  and  many 
of  the  laminae  were  also  smaller  and  thinner.  The  slight 
deficiency  in  weight  of  the  Bush  woman's  Cerebellum, 
*'  depends  essentially,"  according  to  Marshall,  *^  not  on  the 
absence  of  any  parts  or  laminae,  but  on  the  narrowness  of 
these  latter ;  for  they  are  obviously  much  finer  than  in 
the  European  brain."  On  the  whole,  he  considers  that 
"  the  Cerebellum  in  the  Bush  woman  is  very  well  developed, 
and  that,  as  an  organ,  it  is  far  more  completely  evolved 
than  the  Cerebrum.** 


Significance  of  the  High  Convolutional  Development 
of  the  Haman  Cerebral  Hemispheres. 

After  the  preceding  description  of  the  external  configu- 
ration of  the  Human  Brain,  and  now  that  the  differences 
existing  between  it  and  that  of  the  higher  Apes  have  been 
detailed,  such  questions  as  these  may  naturally  present 
themselves  to  the  minds  of  many  readers  : — What  is  the 
precise  significance  of  this  more  complex  convolutional 
development  of  the  Human  Cerebrum  ?  and  what  signi- 
ficance is  to  be  attached  to  the  want  of  symmetrical 
development  in  the  corresponding  Convolutions  of  its  two 
Hemispheres  ? 

It  has  been  previously  pointed  out  that  there  are  three 
principal  types  of  convolutional  arrangement  —  (1)  that 
of  the  Herbivora,  (2)  that  met  with  among  Carnivora  and 
Cetacea,  and  (3)  that  of  Quadrumana  and  Man.  We 
have  seen  also  that  within  each  of  these  great  groups, 
the  development  of  the  Convolutions  peculiar  to  particular 
species  has  hitherto  seemed  to  be  dependent  in  the  main 


408  THE    EXTERNAL    CONFIGURATION 

upon  the  customary  size  attained  by  such  animals* — 
those  that  are  small  may  have  none,  whilst  allied  animals 
of  larger  size  may  have  more  or  less  developed  convolu- 
tions. Yet  it  certainly  cannot  be  said  that  larger  animals 
are  necessarily  more  intelligent  than  smaller  animals. 
.  As  to  the  reason  of  the  greater  convolution al  develop- 
ment met  with  in  larger  animals  Carl  Vogt  says  f  : — 

"  Happily,  mathematics  will  assist  us  here.  On  comparing  two 
bodies  of  similar  form  but  of  different  size,  their  respective 
volumes  vary  as  the  cube  of  their  diameters,  whilst  the  proportion 
of  the  surfaces  is  as  the  square  of  the  diameters,  or,  in  other  words, 
the  volume  of  a  body  increases  more  rapidly  than  the  surface,  and 
this  more  rapidly  than  the  diameter.  Every  artillerist  knows  well 
that  a  twelve  pounder,  though  thrice  as  heavy  as  a  four-pounder, 
does  not  nearly  possess  a  diameter  thrice  as  large  ...  In  applying 
this  principle  to  the  head,  and  especially  the  cranium  of  animals, 
it  will  be  seen  that  in  every  natural  group  or  order  of  mammals, 
the  head,  and  especially  the  cranial  capacity,  stands  in  a  certain 
relation  to  the  body,  which  is  nearly  constant  in  the  various  species 
.  .  .  that  the  surface  of  the  internal  cranial  capacity  is  proportion- 
ately smaller  in  the  larger  animal,  and  that  consequently,  in  order 
to  secure  a  similar  surface  of  grey  matter,  it  must  be  convoluted 
in  the  large  animal,  whilst  it  may  remain  smooth  in  the  small 
animal." 

If  we  look  then  from  a  broad,  general  point  of  view  at 
the  problem  as  to  the  degree  of  importance  to  be  attached 
to  the  great  convolutional  complexity  of  the  brain  of 
Man,  it  is  apt  to  appear,  at  first  sight,  that  this  particular 
feature  may  be  a  necessary  appanage  or  sequence  of  the 
size  of  Man's  body,  as  compared  with  that  of  Monkeys 
and  of  Apes.  Man,  in  respect  of  convolutional  develop- 
ment, appears  to  stand  far  away  at  the  head  of  the 
Quadrumanous  type,  just  as  the  Elephant  stands  at  the 
head  of  the  Herbivorous  type,  and  just  as  the  great  Whales 

*  See  p.  276. 

t  "Lectures  on  Man  "  (Anthrop.  Soc.  Transln.),  p.  105. 


CiiAP.  XXL]  OF    THE    HUMAN    BRAIN.  409 

occupy  a  similar  position  at  the  head  of  the  Carnivorous 
type.  And  further,  the  hrains  of  the  Elephant  and  of 
Cetacea  show  (like  that  of  Man)  a  very  decided  lack  of 
symmetry  in  regard  to  the  precise  disposition  and  shape 
of  corresponding  Convolutions  in  the  two  Hemispheres. 
The  inferences,  therefore,  seem,  at  first,  not  without 
warrant  that  lack  of  symmetry  is  apt  to  go  as  a  kind  of 
mechanical  accident  with  great  complicacy  of  the  Convolu- 
tions, and  that  this  latter  feature,  if  w^e  compare  animals 
of  allied  groups,  is,  in  the  main,  in  relation  with  the  size 
of  their  bodies  and  the  capacities  of  their  Crania. 

But  other  important  considerations  have  to  be  kept  in 
view.  Thus,  as  Vogt  says,  we  must  bear  in  mind  the  fact 
that  the  '  cranial  capacity '  of  Man  is,  in  proportion  to  his 
bulk,  enormously  greater  than  that  of  any  of  the  anthropoid 
Apes,  and  yet  notwithstanding  this  very  greatly  increased 
size  of  the  brain- chamber,  the  increased  area  thus  obtained 
for  superficial  grey  matter  of  Brain,  aoes  not  prove  nearly 
sufficient  for  the  needs  of  Man's  Intellectual  and  Moral 
Life :  it  has  still  to  be  increased  by  the  occurrence  of 
further  secondary  foldings  in  the  Cerebral  Convolutions. 

A  striking  illustration  of  these  all- important  considera- 
tions is  to  be  found  in  the  fact  that  the  convolutional 
development  of  the  Gorilla's  brain  is  much  simpler  than 
that  of  Man's,  although  the  cranial  capacities  even  of  the 
lowest  Men  are  so  much  greater  than  that  of  the  Grorilla, 
and  even  though  in  bulk  of  body  the  great  Ape  often  far 
surpasses  them.  We  have  therefore  increased  complicacy 
of  Convolution  showing  itself  in  the  brain  of  Man  under 
such  doubly  adverse  general  conditions  as  to  make  its 
existence  all  the  more  significant  of  the  enormous  advance 
which  has  actually  taken  place  in  the  development  of  the 
Cerebrum. 

Again,    seeing  that   the  increased  convolutional    com- 


410  CONFIGURATION    OF    BRAIN. 

plexity  of  the  Cerebrum  in  higher  as  compared  with  lower 
Human  Eaces  is  also  associated  with  an  enormous  increase 
in  '  cranial  capacity '  and  weight  of  Brain  —  though 
bodily  stature  remains  practically  the  same — we  have  here 
further  evidence  as  to  the  vast  development  of  the 
Cerebral  Hemispheres  that  has  taken  place  during  the 
long  roll  of  centuries,  whilst  the  ancestors  of  present 
civilized  races  have  been  gradually  raising  themselves 
from  pristine  states  of  savagery  and  barbarism. 

The  high  convolutional  development  of  the  brain  of 
Man  is,  therefore,  a  matter  of  altogether  greater  signifi- 
cance than  the  same  feature  in  Elephants  and  Cetacea, 
seeing  that  it  clearly  is  not  in  him,  as  it  is  to  a  consider- 
able extent  with  tli^m,  a  mere  correlative  of  great  com- 
parative size  of  body. 

It  is  quite  possible,  however,  that  the  relation  between 
high  convolutional  complexity  of  the  Human  Cerebrum  and 
high  Intellectual  and  Moral  Attainments  may  be  general, 
rather  than  special  and  invariable.  This  relation  may, 
indeed,  be  very  similar  to  that  which  has  been  shown  to 
obtain  in  human  beings  between  high  Brain-weights  and 
superior  Mental  Attainments  and  Powers.  Prevailing 
tendencies  decidedly  favour  such  coincidences,  and  yet, 
as  we  have  seen,  notable  exceptions  maj^  from  time  to 
time  be  encountered.  In  subsequent  chapters  it  will  bo 
pointed  out  that  there  is  a  functional  inequality  between 
the  two  Cerebral  Hemispheres,  so  that  the  asymmetrical 
development  of  their  otherwise  corresponding  convolu- 
tions may  be,  at  least  in  part,  due  to  this  fact. 


CHAPTEE  XXII. 

FEOM    BRUTE    TO    HUMAN    INTELLIGENCE. 

**  Man  as  a  being  who  reasons  is  dependent  upon  tlie 
form  of  Language  which  he  employs,  to  aa  extent  that 
can  scarcely  be  over-estimated.  It  is  by  virtue  of  this, 
in  great  part,  that  he  attains  to  such  skill  and  excellence 
in  the  carrying  on  of  complex  mental  processes.  And  if, 
in  attempting  to  bridge  in  the  faintest  way  the  great 
intellectual  and  moral  gap  which  sunders  man  from  the 
highest  of  the  inferior  animals,  we  say  that  he  alone  is 
possessed  of  the  power  of  speaking  and  of  using  Articulate 
Language,  we  probably  fix  upon  that  power  which,  infi- 
nitely above  all  others,  has  had  to  do  with  the  gradual 
progress  that  seems  to  have  taken  place  during  the  lapse 
of  ages — a  progress  which  has  enabled  particular  races  of 
man  to  advance  through  the  multitadinous  grades  of 
civilization  intervening  between  those  who  lived  in  the 
condition  of  savages,  and  those  who  now  constitute  the 
flower  of  European  civilization.  If  then  the  possession  of 
Artieuiate  Speech,  with  the  superadded  accomplishments 
growing  out  of  this,  of  transmitting  thought  by  means  of 
written  and  printed  symbols,  have  had  such  an  over- 
whelming influence  in  aiding  certain  races  to  elevate 
themselves  out  of  a  condition  of  the  rudest  barbarism,  it 
seems  even  more  certain  still  that  Thought  in  all  its 
higher  modes  could  not  be  carried  on  at  all  without  the 
aid  of  Language  of  some  kind." 


412  FROM    BRUTE 

This  passage,  which  formed  the  introduction  to  an 
article  on  "  The  Physiology  of  Thinking,"  written  some 
years  ago,*  may  be  taken  as  the  text  of  the  present 
chapter. 

Views  very  similar  to  these  had  previously  been  enforced 
by  Herbert  Spencer,  Huxley,  and  others,  and  they  have 
grown  much  in  public  recognition  during  the  intervening 
period,  especially  through  the  able  advocacy  of  one  whose 
loss  we  have  now  to  deplore.  Though  the  doctrines  ex- 
pressed by  G.  H.  Lewes  were  not  perhaps  so  novel  as  his 
language  seems  to  imply,  yet  he  lent  them  new  force,  and 
developed  them  in  a  fuller  and  more  precise  manner  than 
had  been  done  by  other  writers. 

The  most  obvious  use  of  Language  is  of  course  as  a 
means  of  definite  communication  between  man  and  man. 
In  his  '^  Laws  of  Thought,"  Thomson  says  (pp.  37— 39  and 
47):  ''We  might  dispense  with  articulate  speech  for 
certain  purposes,  and  might  make  gestures  and  changes 
of  the  countenance,  which  are  the  language  of  action, 
supply  its  place.  But  actions  and  the  play  of  features, 
whilst  they  serve  to  express  love  or  hatred  for  some 
present  object,  need  of  food  or  rest,  joy  or  sorrow,  can 
but  express  a  very  small  and  confined  list  of  thoughts,  if 
we  would  indicate  our  feelings  towards  an  absent  person, 
or  our  wish  for  something  at  a  distance,  or  would  direct 
attention  to  some  inward  state  or  sentiment  .  .  .  Hence 
it  is  necessary  to  appropriate  to  every  object  a  signal, 
always  available,  which  all  men  by  a  tacit  convention 
accept  as  a  substitute  for  the  object,  and  which,  there- 
fore, recalls  the  object  to  the  fancy  whenever  it  is 
employed ;  and  such  a  signal  is  a  noun  or  name  .... 
Names,  however,  are  representatives  of  things  ;  and  the 
difierent  states  of  things  must  find  an  expression  likewise ; 
*  "  Fortnightly  Review,"  January,  1809. 


Chap.  XXII.]         TO    HUMAN    I?sTELLIGENCE.  413 

lieDce  the  need  of  adjectives  and  verbs.  The  verb  has 
the  power  of  assigning  to  the  thing  at  a  particular  time 
the  condition  of  being,  doing,  or  undergoing  something. 
.  .  .  When  two  or  more  names  come  together,  it  is 
frequently  necessary  to  express  the  mutual  relation  in 
which  they  stand  ;  a  thing  may  be  to,  from,  by,  in,  near, 
above,  below  another,  and  prepositions  are  inserted  to 
determine  this.  Here  then  are  the  four  principal  parts 
of  speech,  substantives,  or  names  to  express  substantives, 
adjectives  to  stand  for  attributes,  prepositions  to  denote 
relations,  and  a  single  verb  to  assign  attributes  or  rela- 
tions to  substantives  at  a  determinate  time." 

**  The  various  parts  of  speech  took  their  origin  from  the 
noun  and  verb,  or  possibly  from  the  noun  alone.  Many 
instances  can  be  found  of  adverbs  and  prepositions  which 
are  distinctly  substantives,  and  of  conjunctions  which  are 
but  parts  of  verbs.  Then  the  close  connexion  between 
the  verb  and  noun  is  indicated  by  the  number  of  words 
which,  in  our  own  language,  are  both  verb  and  noun,  and 
only  distinguished  by  mode  of  pronunciation." 

"It  is  impossible  to  trace  the  growth  of  language  with 
certainty;  but  it  is  most  probable  that  many  of  the  roots 
of  the  primitive  language  were  originally  imitations  of  the 
various  sounds  emitted  by  things  in  the  natural  world. 
A  bird  or  animal,  perhaps,  received  a  name  derived  from, 
and  resembling,  its  own  peculiar  utterance.  The  cry  or 
exclamation  that  man  emitted  instinctively  under  the 
pressure  of  some  strong  feeling,  would  be  consciously 
reproduced  to  represent  or  recall  the  feeling  on  another 
occasion  :  and  it  then  becomes  a  word  or  vicarious  sign. 
"Where  natural  sounds  failed,  analogy  would  take  the 
place  of  imitation  ;  words  harsh  and  difficult  to  pronounce 
w^ould  be  preferred  to  stand  for  unpleasing  objects,  over 
those  of  a  more  bland  and  facile  character,  which  would 


414  FROM    BRUTE 

he  appropriated  to  pleasant  things  and  conceptions.. 
There  agreement  among  those  who  used  the  language, 
would  be  sufficient  to  stamp  a  vocal  sound  as  the  uame  of 
a  certain  object,  where  neither  imitation  nor  analogy 
suggested  one.  But  these  original  roots,  the  simplest 
form  of  substantives,  would  gradually  become  less  and 
less  discernible  as  the  language  grew  richer  and  more 
intricate.  Wherever  new  arts  are  practised,  we  may 
easily  find  opportunities  of  watching  the  growth  of  new 
names  for  its  instruments  and  processes,  guided  by  these 
three  principles,  imitation,  analogy,  and  mere  con- 
vention." 

■"  These  are  but  slender  hints,"  says  the  author  (now 
Archbishop  of  York),  ''of  the  direction  in  which  profound 
and  acute  researches  have  been  made.  And  I  do  not 
think  that  such  attempts  to  dissect  and  analyze  language, 
pursued  with  proper  caution,  tend  at  all  to  lower  our 
estimate  of  the  importance  of  the  gift  of  speech,  or  of 
its  marvellous  nature."  This  will,  perhaps,  be  a  con- 
solatory admission  to  many  persons.  It  is  further  not 
without  interest  to  find  another  highly  acute  and  philoso- 
phical Doctor  of  Divinity  writing  as  follows  *  : — 

"  In  inquiring  how  far  the  same  process,  can  account 
for  the  invention  of  language,  which  now  takes  place  in 
the  learning  it,  the  real  question  at  issue  is  simply  this  : 
Is  the  act  of  giving  names  to  individual  objects  of  sense  a 
thing  so  completely  beyond  the  power  of  a  man  created  in 
the  full  maturity  of  his  faculties,  that  we  must  suppose  a 
Divine  Instructor  performing  precisely  the  same  office  as 
is  now  performed  for  the  infant  by  his  mother  or  his 
nurse ;  teaching  him,  that  is,  to  associate  tJds  sound  with 
tJiis  sight?  "  This  question  maybe  asked  in  the  interests 
of  a  human  race  naturally  evolved,  with  as  much  cogency 
*  Dr.  Mansel,  "  Prolegomena  Logica,"  p.  20. 


Chap.  XXIL]  TO    HUMAN    INTELLIGENCE  415 

as  in  reference  to  the  hypothetical  man  "  created  in  the 
full  maturity  of  his  faculties." 

An  endowment  like  Articulate  Speech,  when  once  started 
— whether  by  some  hidden  and  unknown  process  of  natural 
development,  or  as  a  still  more  occult  God-sent  gift  to  Man 
— was  by  its  very  nature  almost  certain  to  have  led  its  pos- 
sessors by  degrees  along  an  upward  path  of  cerebral  devel- 
opment. How  slow  and  tardy  the  process  has  been  we  are 
now  beginning  dimly  to  perceive,  by  reason  of  those  re- 
searches which  have  made  known  to  us  the  great  antiquity 
of  the  Human  Race  and  the  far  remote  period  of  Man  s 
appearance  upon  this  Earth. 

Anterior  to  historical  epochs,  the  Men  who  were  the 
contemporaries  of  the  great  Mammoths,  whose  remains  are 
found  in  the  Post-Tertiary  Drift,  those  of  the  Bone-Caves, 
those  of  the  Shell-heaps  and  the  Peat-bogs,  as  well  as  those 
of  the  Cromlech  period  and  the  Early  Lake-dwellings,  lived 
for  untold  ages  in  a  state  of  simplicity  and  barbarism  far 
greater  than  that  which  still  continues  among  many  of  the 
savage  and  semi-savage  races  covering  so  large  a  propor- 
tion of  the  Earth's  surface. 

Progress,  in  the  early  stages  of  human  history,  was 
necessarily  so  slow  as  to  have  seemed  almost  absent,  even 
if  we  mark  time  by  centuries.  Gradually,  however,  as  a 
nomad  life  gave  place  to  a  more  complex  communal  life, 
the  advantages  of  co-operation  would  show  themselves  in 
many  ways.  The  commencement  of  a  developing  Social 
Organization  necessarily  entails  a  greater  diversity  in 
the  relations  of  man  with  man,  which  would  naturally 
become  reflected  in  their  Language,  and  proportionately 
increase  the  area  of  their  thought-processes,  by  giving 
birth  to  new  exercises,  or,  at  all  events,  by  greatly  strength- 
ening   certain    previously    embryonic     mental     processes. 


416  FROM    BRUTE 

Increased  Sympathy,  as  well  as  an  increased  recognition 
by  each  unit  of  the  *  social  organism  '  of  what  he  might  do 
for  the  gratification  of  his  own  wants  or  desires  without 
bringing  pain  upon  himself  through  the  anger  of  his 
fellovvSj  would  gradually  teach  him  the  necessity  of  sub- 
ordinating within  certain  limits  his  realization  of  egoistic 
impulses,  and  the  need,  even  for  the  sake  of  his  own 
happiness,  of  continually  bearing  in  mind  the  wants  and 
wishes  of  his  fellow-men. 

Sympathy  we  have  seen  to  have  been  begotten  even 
in  the  breasts  of  many  dumb  animals,  when  they  have 
learned  to  recognize  in  their  fellows  the  outward  signs  of 
that  which  they  remember  as  a  condition  of  past  distress 
for  themselves.  The  ideal  recurrence  of  such  a  state, 
coupled  with  a  perception  implying  the  similar  present 
suffering  of  another,  prompts  to  actions  for  its  relief.  In 
such  exercise  of  mere  brute  Sympathy,  we  have  one  of  the 
most  important  germs  of  those  altruistic  feelings  which 
attain  so  much  breadth  and  power  in  higher  races  of  Man. 

Equally  important,  however,  among  savage  races,  are 
those  limitations  which  'expediency'  compels  the  individual 
to  recognize,  as  imposed  by  his  fellow-men  upon  the 
freedom  of  his  own  actions.  Such  considerations,  in 
concert  perhaps  with  a  strengthening  Sympathy,  gra- 
dually tend  to  build  up  within  him  an  inward  monitor,  or 
*  Conscience,'  at  the  same  time  that  there  arise  embryo 
notions  of  Eight  and  Duty,  constituting  the  foundations 
of  a  dawning  '  Moral  Sense.'  Having  such  an  origin,  the 
impulses  of  such  a  '  faculty  '  cannot  fail  to  harmonize  with 
prevalent  opinions  and  influences.  As  G.  H.  Lewes 
says* : — 

"There  cannot  be  moral  relations  apart  from  Society  ....  The 
Intellect  and  the  Conscience  are  social  functions;  and  their  special 

*  "Problems  of  Life  and  Mind,"  vol.  i.  p.  173. 


Chap.  XXII.]         TO    HUMAN    INTELLIGENCE.  417 

manifestations  are  rigorously  determined  by  social  Statics,  i.e.  the 
state  of  the  Social  Organism  at  the  time  being,  which  they  in  their 
turn  determine.  The  Language  we  think  in  and  the  conceptions 
we  employ,  the  attitude  of  our  minds,  and  the  means  of  investiga- 
tion, are  social  products  determined  by  the  activities  of  the 
Collective  Life.  The  laws  of  intellectual  progress  are  to  be  read 
in  History,  not  in  the  individual  experience.  We  breathe  the 
social  air;  since  what  we  think  greatly  depends  on  what  others 
have  thought." 

The  power  of  Language  in  aiding  cerebral  development 
and  thinking  processes,  although  it  must  have  been  great 
from  the  first,  and  ever  tending  to  increase,  did  not  reveal 
itself  so  forcibly  till  means  had  been  adopted  for  the 
preservation  and  communication  of  human  experience 
and  thought  from  generation  to  generation,  by  means 
either  of  Hieroglyphics  or  more  modern  forms  of  Writing. 
When  these  came  into  common  use,  and  when,  more  espe- 
cially, Printing  had  been  adopted  and  books  began  to 
circulate,  then  at  last  Language  began  to  exercise  its  full 
influence  as  an  aid  to  and  developer  of  Thought.  For 
although  oral  tradition  is  vastly  better  than  qo  means  afc 
all,  for  communicating  '  experience  '  and  Thoughts  from 
one  generation  to  another,  it  is  poor  indeed  compared 
with  the  facilities  afforded  by  printing  and  the  common 
distribution  of  Books.  With  these  Jattei-  means  in  exist- 
ence, the  Thoughts  of  man  may  go  on  accumulating  from 
age  to  age,  forming  a  record  of  his  complex  relations  to 
nature  generally,  to  his  fellows,  and  to  that  Social  Organ- 
ism, in  particular,  of  which  he  and  they  form  parts. 

Language  is,  however,  indispensable  not  merely  to  thf 
communication,  but  to  the  formation  cf  Thought,  since  it 
favours  the  birth  of  Concepts  or  General  Notions,  and  is 
essential  both  for  their  '  preservation  '  and  familiar'  use.' 

Li  his  "Prolegomena  Logica"  (pp.  19.  20,  23-31), 
Mansel  says : — 


418  FROM    BRUTE 

.  "To  the  child  learning  to  speak,  words  are  not  the  signs  of 
thoughts,  but  of  intuitions  ['Presentations  of  Sense']:  the  words 
tnan  and  liorse  do  not  represent  a  collection  of  attributes,  but  are 
only  the  name  of  the  individual  now  before  him.  It  is  not  until 
the  name  has  been  successively  appropriated  to  various  individuals, 
that  reflection  begins  to  inquire  into  the  common  features  of  the 
class.  Language,  therefore,  as  taught  to  the  infant,  is  chrono- 
logically prior  to  thought  and  posterior  to  sensation  ....  All 
concepts  are  formed  by  means  of  signs  which  have  previously  been 
representative  of  individual  objects  only  ....  Similarities  are 
noticed  earlier  than  differences ;  and  our  first  abstractions  may  be 
said  to  be  performed  for  us,  as  we  learn  to  give  the  same  name  to 
individuals  presented  to  us  under  slight,  and  at  first  unnoticed, 
circumstances  of  distinction.  The  same  name  is  thus  applied  to 
different  objects,  long  before  we  learn  to  analyze  the  growing 
powers  of  speech  and  thought,  to  ask  what  we  mean  by  each 
several  instance  of  its  application,  to  correct  and  fix  the  significa- 
tion of  words  used  at  first  vaguely  and  obscurely.  To  point  out 
each  successive  stage  of  the  process  by  which  signs  of  intuition 
bpcome  grii.lually  signs  of  thought,  is  as  impossible  as  to  point  out 
the  several  moments  at  which  the  growing  child  receives  each 
successive  increase  of  its  stature." 

This  important  opinion  of  Mansel,  that  without  *  signs  * 
or  Names  we  could  not  form  Concepts  at  all,  is  in  opposi- 
tion to  a  commonly  entertained  view,  that  "  we  must 
have  had  the  concept  before  we  could  have  given  it  a 
name,"  but  it  is  one  which,  as  J.  S.  Mill*  puts  it, 
Mansel  justly  enough  bases  upon  the  view  that '' names 
when  first  used  are  names  only  of  individual  objects,  but 
being  extended*  from  one  object  to  another  under  the  law 
of  Association  by  Ee semblance,  they  become  specially 
associated  with  the  points  of  resemblance,  and  thus 
generate  the  Concept."  Sir  William  Hamilton  thinks, 
however,  that  we  may  be  able  to  '  form  *  simple  concepts, 
though  scarcely  to  *  preserve '  them  without  the  aid  of 

*  "  Exam,  of  Sir  Wm.  Hamilton's  Philosophy,"  p.  324 


Chap.  XXIL]  TO    HUMAN    INTELLIGENCE.  419 

signs.  "A  word  or  sign,"  lie  says,*  "  is  necessary  to 
give  stability  to  our  intellectual  progress,  to  establish 
each  step  in  our  advance  as  a  new  starting-point  for  our 
advance  to  another  beyond.  A  country  may  be  overrun 
by  an  armed  host,  but  it  is  only  conquered  by  the 
establishment  of  fortresses.  Words  are  fortresses  of 
thought.  They  enable  us  to  realize  our  dominion  over 
what  we  have  already  overrun  in  thought ;  to  make  every 
intellectual  conquest  the  basis  of  operations  for  others 
still  beyond  ....  Though,  therefore,  we  allow  that 
every  movement  forward  in  language  must  be  -determined 
by  an  antecedent  movement  forward  in  thought ;  still, 
unless  thought  be  accompanied  at  each  point  of  its 
evolution,  by  a  corresponding  evolution  of  language,  its 
further  development  is  arrested."  On  a  previous  page  he 
had  said  : — "  The  concept  thus  formed  by  an  abstraction 
of  the  resembling  from  the  non-resembling  qualities  of 
objects,  would  again  fall  back  into  the  confusion  and 
infinitude  from  which  it  has  been  called  out,  were  it  not 
rendered  permanent  for  consciousness,  by  being  fixed  and 
ratified  in  a  verbal  sign." 

While  there  seems  to  be  good  reason  for  believing 
with  Mansel,  that  General  Notions  or  Concepts  cannot  be 
formed  without  the  aid  of  Signs,  this  doctrine  must  be 
received  with  a  certain  reservation,  which  tends,  however, 
to  support  the  opinion  of  Sir  William  Hamilton.  Signs 
are  necessary ;  but,  for  the  formation  of  simple  General 
Notions,  '  Visual  Images  '  may  take  the  place  of  Words. 

On  this  subject  J.  S.  Mill  says: — "The  signs  need  not  be  arti- 
ficial; there  are  such  things  as  natural  signs.  The  only  reality 
there  is  in  the  Concept  is,  that  we  are  somehow  enabled  and  led, 
not  once  or  accidentally,  but  in  the  common  course  of  our  thoughts, 
to  attend  specially,  and  more  or  less  exclusively,  to  certain  parts 

*  "  Lectures,"  vol.  iii.  pp.  138-14)0. 


420  FROM    BRUTE 

of  the  presentation  of  sense  or  representation  of  imagmation 
which  we  are  conscious  of.  Now,  what  is  there  to  mate  ns  do  this  ? 
There  must  be  something  which,  as  often  as  it  recurs  either  to  our 
senses  or  to  our  thoughts,  directs  our  attention  to  those  particular 
elements  in  the  perception  or  in  the  idea :  and  whatever  performs 
this  office  is  virtually  a  sign ;  but  it  need  not  be  a  word :  the 
process  certainly  takes  place  to  a  limited  extent,  in  the  inferior 
animals  ;  and  even  in  human  beings  who  have  but  a  small  voca- 
bulary, many  processes  of  thought  take  place  habitually  by  other 
symbols  than  words.  It  is  a  doctrine  of  one  of  the  most  fertile 
thinkers  of  modern  times,  Auguste  Comte,  that  besides  the  logic 
of  signs,  there  is  a  logic  of  images,  and  a  logic  of  feelings.  In 
many  of  the  -familiar  processes  of  thought,  and  especially  in  uncul- 
tured minds,  a  visual  image  serves  instead  of  a  word.  Our  visual 
eensations — perhaps  only  because  they  are  almost  always  present 
along  with  the  impressions  of  our  other  senses — have  a  facility  of 
becoming  associated  with  them.  Hence  the  cnaracteristic  visual 
appearance  of  an  object  easily  gathers  round  it,  by  association,  the 
ideas  of  all  other  peculiarities  which  have,  in  frequent  experience, 
coexisted  with  that  appearance:  and  summoning  up  these  with  a 
strength  and  certainty  far  surpassing  that  of  the  merely  casual 
associations,  which  it  may  also  raise,  it  concentrates  the  attention 
on  them.  This  is  an  image  ^serving  for  a  sign — the  logic  of 
images.  The  same  function  may  be  fulfilled  by  a  feeling.  Any 
strong  and  highly  interesting  feeling,  connected  with  one  attribute 
of  a  group,  spontaneously  classifies  all  objects  according  as  they 
possess  or  do  not  possess  that  attribute.  We  may  be  tolerably 
certain  that  the  things  capable  of  satisfying  hunger,  form  a  per- 
fectly diw-inct  class  in  the  mind  of  any  of  the  more  intelligent 
animals  ;  quite  as  much  so  as  if  they  were  able  to  use  or  understand 
the  word  food."  \. 

Whilst  it  seems  possible,  therefore,  that  simple 
General  Notions  may  be  formed  around  and  called  up 
by  Feelings,  and  consequently  by  the  Images  of  these 
(and  especially  by  Visual  Images),  it  is  also  clear  that 
Words  are  much  more  potent  Signs,  since  in  addition  to 
the  aid  which  they  aftbrd  in  the  formation  of  General 
Notions,  thoy  carry  with  them  the  power  of  being  used 
as  means  of  communicating  Thoughts,  and,  therefore,  of 


CuAp.  XXII.]         TO    HUMAN    INTELLIGENCE.  421 

strengtlieiiiiig  them  by  repetitious  and  mutual  inter- 
cliauges,  during  the  daily  life  of  the  units  of  any  tribe, 
race,  or  nation  of   Human  Beings. 

As  Thomson  says*: — "  Language,  the  closezfittin  g 
di-ess  of  QUI-  t.hmiglifg,  is  always  analytical,  it  does  not 
body  forth  a  mere  picture  of  facts,  but  displays,  the 
working  of  the  mind  upon  the  facts  suhTTiJttP'l  tu  it, 
with  tlie  ordei  m  which  it  reo-nvrls  fhAixL,  ....  the 
same  language  becomes  more  analytic  as  literature 
and  refinement  increase.  This  property  indicates,  as 
we  should  expect,  corresponding  changes  in  the  state 
of  thinking  in  different  nations,  or  in  the  same  at 
different  times.  With  increasing  cultivation,  finer  dis- 
tinctions are  seen  between  the  relations  of  objects,^ 
and  corresponding  expressions  are  sought  for,  to  denote 
them;  because  ambiguity  and  confusion  would  result 
from  allowing  the  same  word,  or  form  of  words,  to 
continue  as  the  expression  of  two  different  things  or 
facts  ....  A  discovery  can  hardly  be  said  to  be  secured, 
until  it  has  been  marked  by  a  name  which  shall  serve  to 
recall  it  to  those  who  have  once  mastered  its  nature,  and 
to  challenge  the  attention  of  those  to  whom  it  is  still 
strange.  Such  words  as  inertia,  affinity,  polarisation, 
gravitation,  are  summaries  of  so  many  laws  of  nature, 
and  are  so  far  happily  chosen  for  their  purpose,  that, 
except  perhaps  the  third,  each  of  them  guides  us  by  its 
etymology  towards  the  nature  of  the  law  it  stands  to 
indicate  ....  Names  then  are  the  means  of  fixing  and 
recording  the  results  of  trains  of  thought,  which  without 
them  must  be  repeated  frequently,  with  all  the  pain  of  the 
first  efTort  ....  As  the  distinctions  between  the  rela- 
tions of  objects  grow  more  numerous,  involved,  and  subtle, 


«  "  Laws  of  Thought,"  p.  28. 
19 


; 


422  FROM    BRUTE 

it  becomes  more  analytic,  to  be  able  to  express  them: 
and  inversely  those  who  are  born  to  be  the  heirs  of  a 
highly  analytic  language,  must  needs  learn  to  think  up  to 
it,  to  observe  and  distinguish  all  the  relations  of  objects, 
for  which  they  find  the  expressions  already  formed,  so 
that  we  have  an  instructor  for  the  thinking  powers  in  that 
speech,  which  we  are  apt  to  deem  no  more  than  their 
handmaid  and  minister." 

Leibnitz,  in  an  important  passage  concerning  the 
symbolical  nature  of  many  of  our  processes  of  cogni- 
tion or  thought,  was  the  first  to  call  attention  to  a  kind 
of  fusion  or  identification  of  Thought  and  Word,  which  is 
habitually  taking  place  in  our  ordinary  mental  processes. 
General  and  abstract  names  or  words  are  often,  as 
Thomson  says,*  "  Symbols  both  to  speaker  and  hearer, 
the  full  and  exact  meaning  of  which  neither  of  them  stops 
to  unfold,  any  more  than  they  regularly  reflect  that  every 
sovereign  which  passes  through  their  hands  is  equivalent 
to  240  pence.  Such  words  as  the  state,  happiness, 
liberty,  creation,  are  too  pregnant  with  meaning  for  us 
to  suppose  that  we  realize  their  full  sense  every  time  wo 
read  or  pronounce  them.  If  we  attend  to  the  working  of 
our  own  minds,  we  shall  find  that  each  word  may  be 
used,  and  in  its  proper  place  and  sense,  though  perhaps 
none  or  few  of  its  attributes  are  present  to  us  at  the 
moment." 

The  process  of  Conception  by  which  such  general  or 
Abstract  Notions  are  arrived  at,  is  only  possible  by  a  prior 
use  of  Language ;  and  the  marking  of  these  com]3lex 
notions  by  Words  subsequently  to  be  used  as  '  symbols '  or 
counters  equivalent  to  such  Notions,  is  a  fusion  into  one 
of  cerebral  Thought-processes  and  Word-processes- -the 
Word  in  future  is  the  Thought. 

*  Lcc.  cit.  p.  36. 


Chap.  XXII.]  TO    HUMAN    INTELLIGENCE.  423 

After  these  brief  observations  concerning  the  growth 
and  functions  of  Language,  and  as  to  its  use  in  aiding 
tjie_development  of  Mind,  we  may  turn  to  the  views  of 
G.  H.  Lewes  concerning  the  transition  from  Brute  to 
Human  InteUigence,  and  on  the  subject  of  the  further 
powerful  influence  exerted  by  Language,  when  acting  in 
concert  with  Social  Influences  generally — the  influences 
that  is,  which  are  brought  to  bear  upon  Men  as  units  in  a 
gradually  developing  Social  Organization. 

He  says*  :  "  That  animals  have  sensations,  appetites, 
emotions,  instincts,  and  intelligence — that  they  exhibit 
memory,  expectation,  judgment,  hope,  fear,  joy — that 
they  learn  by  experience,  and  invent  new  modes  of  satis- 
fying their  desires,  no  philosopher  now  denies.  And  yet 
the  gap  between  animal  and  human  intelligence  is  so 
wide,  that  Philosophy  is  sorely  puzzled  to  reconcile  the 
undeniable  facts."  .  .  .  "Animals  having  organs  closely 
resembling  our  own,  and  feelings  closely  resembling  our 
own,  have  little  or  nothing  of  the  highest  order  of  mental 
activity ;  Animals  are  intelligent,  but  have  no  Intellect ; 
they  are  sympathetic  but  have  no  Ethics ;  they  are 
emotive,  but  have  no  Conscience."  .  .  .  When  it  is 
said  that  Animals  however  intelligent  have  no  Intellect, 
the  meaning  is  that  flTf^yViRVA^pPiYPpfiniTo  nnrl  JTrrlrmTA-nr^j  ^ 
but  no  conceptions,  no  genei-al  ideas,  no  symbols  for 
logical  operations. f  They  are  intelligent,  for  we  see 
them  guided  to  action  by  Judgment;  they  adapt  their 
actions  by  means  of  guiding  sensations,  and  adapt  things 
to  their  ends.  Their  mechanism  is  a  sentient,  intelligent 
mechanism.     But  they  have  not  Conception,  or  what  we 

*  "  Problems  of  Life  aud  Mind,"  vol.  i.  pp.  152,  154,  and  156. 

t  To  a  limited  extent,  as  already  stated,  there  is  reason  to  believe 
tliat  animals  do  carry  on  some  such  mental  processes,  not  ot  course 
by  Word  Symbols,  but  by  means  of  Visual  Iniciges. 


424  FROM    BRUTE 

specially  designate  as  Thought,  i.e,  that  logical  function 
which  deals  with  generalities,  ratios,  symbols,  as  Feeling 
deals  with  particulars  and  objects,  a  fnnctlon  sustained 
hy  and  subservient  to  impersonal,  social  ends.  Taking 
Intelligence  in  general  as  the  discrimination  of  means  to 
ends — the  guidance  of  the  Organism  towards  the  satisfac- 
tion ol  its  impulses — we  particularize  Intellect  as  a  highly 
differentiated  mode  of  this  function,  namely,  as  the 
discrimination  of  symbols.  This  differs  from  the  rudi- 
mentary mode,  out  of  which  it  is  nevertheless  an  eyolution, 
as  European  Commerce  differs  from  the  rudimentary 
Barter  of  primitive  tribes.  Commerce  is  impossible 
except  under  complex  social  conditions  out  of  which  it 
springs ;  and  its  operations  are  mainly  carried  on  by 
means  of  symbols  which  take  the  place  of  objects ;  the 
bill  of  invoice  represents  the  cargo  ;  the  merchant's  signa- 
ture represents  the  payment.  In  like  manner  Intellect  is 
impossible  until  animal  development  has  reached  the 
human  social  stage  ;  and  it  is  at  all  periods  the  index  of 
that  development ;  its  operations  are  likewise  carried  on 
by  means  of  symbols  (Language)  which  represent  real 
objects,  and  can  at  any  time  be  translated  into  feelings 
.  .  .  between  the  extremes  of  human  Intelligence — say  a 
Tasmanian  and  a  Shakespeare — there  are  infinitesimal 
gradations,  enabling  us  to  follow  the  development  of  the 
one  into  the  other,  without  the  introduction  of  any  essen- 
tially new  factor.  But  between  animal  and  human  Intel- 
ligence there  is  a  gap,  which  can  only  be  bridged  over  by 
an  addition  from  without.  That  bridge  is  the  Language 
of  symbols,  at  once  the  cause  and  effect  of  Civilization." 

Again,,  the    same    writer    remarks*: — "An    animal 
suffers  from  a  physical  calamity,  seeks  to  escape  from  it, 

*  Log.  cit.  pp.  1(58,  169. 


Chaf.  XXII.]  TO    HUMAN    INTELLIGENCE.  425 

but  never  seeks  to  understand  and  modify  its  causes. 
The  savage  also  suffers,  and  seeks  to  escape.  But  he 
\Yonders,  speculates  on  the  causes,  hopes  to  master  them 
by  invocations,  or  incantations.  The  civilized  man  tries 
to  understand  the  causes,  that  he  may  modify  them  when 
they  are  modifiable,  and  resign  himself  to  them  when 
they  are  unmodifiable.  The  animal  has  only  the  Logic 
of  Feeling  to  guide  his  actions.  He  observes  and  con- 
cludes, nevei  explains.  The  man  has  besides  this  the 
Logic  of  Signs  :  he  observes  and  explains  the  visible 
series  by  an  invisible  series.  The  one  has  only  know- 
ledge of  particular  facts,  the  other  a  knowledge  of  general 
facts." 

In  the  progress  of  Intellectual  Development  there  is 
exhibited  an  ever-increasing  tendency  to  deal  with  more 
and  more  remote  Conceptions,  and  with  indirect  mental 
processes  which  detach  the  mind  further  and  further  from 
Sensible  Observation.  It  may  be  illustrated,  as  G.  H. 
Lewes  says,"*  by  the  stages  of  numerical  calculation. 

"Man  begins  by  counting  things,  grouping  tlie'tn  visibly.  He 
then  learns  to  count  simply  the  numbers,  in  the  absence  of  the 
things,  using  his  fingers  and  toes  for  symbols.  He  then  substitutes 
abstract  signs,  and  Arithmetic  begins.  From  this  he  passes  to 
Algebra,  the  signs  of  which  are  not  onl}^  abstract  but  general ;  and 
now  he  calculates  numerical  relations  not  numbers.  From  this  he 
passes  to  the  higher  calculus  of  relations  ....  In  consequence  of 
this  development  of  Intellect — i.e.,  of  the  interest  in  remote  means 
substituted  for  direct  ends — man  acquires  his  immense  superiority 
over  animals  in  achieving  the  final  end.  It  is  thus,  and  thus  only, 
that  he  is  enabled  to  modify  the  course  of  events.  It  is  thus  that 
Sentience  becomes  Science,  facts  are  condensed  into  laws,  and 
direct  vision  is  multiplied  and  magnified  by  remote  prevision." 

"  The  absurdity  of  supposing  that  any  ape  cculd,  under  any 
normal  circumstances,  construct  a  scientific  theory,  analyze  a  fact 
into  its  component  factors,  frame  to  himself  a  picture  of  the  life  led 

*  Loc.  cit.  p,  171. 


426  FROM    BRUTE 

by  his  an<;estors,  or  consciously  regulate  his  conduct  with  a  view- 
to  the  welfare  of  remote  descendants,  is  so  glaring,  that  we  need 
not  wonder  at  profoundly  meditative  minds  having  been  led  to 
reject  with  scorn  the  hypothesis  which  seeks  for  an  explanation  of 
human  Intelligence  in  the  functions  of  the  bodily  organism  common 
to  man  and  animals,  and  having  had  recourse  to  the  hypothesis  of 
a  spiritual  agent  superadded  to  the  organism." 

"  But,"  he  adds,*  "the  savage  is  not  less  incompetent  than  the 
animal  to  originate  or  even  understand  a  philosophical  conception; 
the  peasant  would  be  little  better  than  the  ape,  in  presence  of  the 
l^roblems  of  abstract  science;  and  it  would  be  hopeless  to  expect 
cither  of  them  to  weigh  the  stars,  or  to  understand  the  equations 
of  curves  of  double  curvature.  Nor  are  the  moral  conceptions  of 
the  savage  much  higher  than  those  of  the  animal.  His  language 
is  without  terms  for  Justice,  Sin,  Crime:  he  has  not  the  ideas. 
He  understands  generosity,  pity,  and  love,  little  better  than  the 
dog  or  the  horse  does.  His  intelligence  is  mainly  confined  to 
perceptions  and  sentiments.  His  aims  are  almost  all  immediate 
and  practical,  rarely  remote,  never  theoretical.  The  most  intelli- 
gent inhabitants  of  Guiana,  though  far  removed  from  primitive 
Savagery,  could  not  believe  that  Humboldt  had  left  his  own 
country  and  come  to  theirs  '  to  be  devoured  by  mosquitos  for  the 
sake  of  measuring  lands  which  were  not  his  own.'  ....  All  the 
materials  of  Intellect  are  images  and  symbols,  all  its  processes  are 
operations  on  images  and  symbols.  Language — which  is  wholly 
a  social  product  for  a  social  need — is  the  chief  vehicle  of  symbol- 
ical operation,  and  the  only  means  by  which  abstraction  is  etfected. 
Without  Language  there  can  be  no  meditation,  no  theory,  no 
Thought,  in  the  special  meaning  of  that  term." 

But  as  we  have  already  hinted,  concurrently  with  tho 
development  of  Man's  Intellectual  Nature,  there  gradually 
emerges,  in  response  to  other  aspects  of  the  same  general 
influences  and  conditions,  what  is  known  as  his  Moral 
Nature. 

As  Lewes  saysf: — "Man's  individual  functions  arrse 
in  relations  to  the  Cosmos  ;  his  general  functions  ariso 
in   relations  to   the  Social  Medium  ;    thence  Moral  Lifa 

*  Loc.  cit.  pp.  158, 1G7.  t  Loc.  cit.  pp.  159, 173. 


CiiAV.  XXII.]         TO    HUMAN    INTELLIGENCE.  427 

emerges.  All  the  animal  Impulses  become  blended  with 
human  Emotions.  In  the  process  of  evolution,  starting 
from  the  merely  animal  appetite  of  sexuality,  we  arrive  at 
the  purest  and  most  far-reaching  tenderness ;  from  the 
merelyanimalpropertyof  Sensibility  we  arriveat  the  noblest 
heights  of  Speculation.  The  Social  Instincts,  which  are 
the  analogues  of  the  individual  Instincts,  tend  more  and 
more  to  make   Sociality   dominate  Animality,   and   thus 

subordinate  Personality  to  Humanity Thus  the 

human  Intellect  emerges  from  animal  Intelligence,  and 
develops  a  vast  independent  creation,  having  the  whole 
Cosmos  and  Humanity  for  its  material.  Concurrently 
with  this,  the  Moral  Intelligence  develops  its  system. 
Both  Intellect  and  Conscience  are  products  of  the  animal 
impulses  and  social  impulses  acting  and  reacting.  While 
the  Intellect  is  mainly  occupied  with  the  relations  of  the 
Cosmos  and  its  History,  having  the  ultimate  aim  of 
making  these  subservient  to  practical  needs,  the  Con- 
science, or  Moral  Intelligence,  is  mainly  occupied  with  the 
relations  of  humanity — human  needs  and  human  actions 
— having  the  ultimate  aim  of  conforming  our  conduct  to 
those  relations,  harmonising  our  impulses  with  the 
impulses  of  others,  thus  aiding  others  and  gratifying 
ourselves.'* 


CHAPTEK  XXIIL 

THE    INTERNAL    STRUCTURE    OF    THE    HUMAN   BRAIN. 

The  internal  structure  of  the  Human  Brain  is  so  complex, 
and  at  the  same  time  so  yevy  imperfectly  known,  as  to  make 
it  difficult  to  give  any  account  of  it  which  shall  be  intel- 
ligible to  the  majority  of  readers.  The  adequate  com- 
prehension even  of  its  general  plan  or  groundwork  will 
require  a  full  amount  of  attention.  In  the  present  chap- 
ter multitudes  of  technical  details,  whose  significance  is 
either  unknown  or  incapable  of  being  appreciated  by  any 
one  who  has  not  previously  made  a  close  study  of  tne 
subject,  will  be  excluded.  The  discussion  of  such  details 
may  be  found  in  more  technical  and  purely  anatomical 
works. 

By  tracing  upwards  some  of  the  more  elementary  forms 
of  the  Nervous  System  met  with  among  Invertebrates, 
and  afterwards  describing  the  principal  external  or  grosser 
variations  of  the  Brain  as  they  present  themselves  in  the 
Vertebrate  Series,  the  best  preparation  has  perhaps  been 
made  for  such  a  study  of  the  structure  of  the  Brain  of 
Man,  as  is  compatible  with  the  plan  of  this  work.  The 
reader  will  thus  have  been  gradually  introduced  to  the 
representatives  of  the  several  parts  of  the  Human  Brain, 
and  the  description  of  this  organ  ought  thereby  to  have 
been  rendered  both  simpler  and  more  interesting  than  it 
would  otherwise  have  been.  No  parts  absolutely  new  will 
be  met  with,  though  it  will  not  be  difficult  to  note  many 


Chap.  XXIIL]      INTERNAL  STRUCTURE  OF  BRA [N.  429 

differences  in  regard  to  the  absolute  or  relative  size  of 
divisions  of  the  Brain,  with  which  the  reader  is  already- 
familiar  from  their  occurrence  in  lower  animals.  The 
possession  of  a  basis  of  comparison  of  this  kind  can 
scarcely  fail  to  infuse  great  additional  interest  into  the 
study  of  the  brain  of  Man,  and  it  will  often  obviate  the 
necessity  for  anything  like  lengthy  descriptions. 

What  is  to  be  said  in  this  chapter  as  to  the  internal  structure  of 
the  Human  Brain  may  be  most  conveniently  grouped  under  the 
following  headings: — (1)  Internal  Topography  ot  the  Human 
Brain ;  (2)  Distribution  of  the  Fibres  composing  the  Cerebral 
Peduncles,  with  an  account  {a)  ot  their  relation  to  the  Thalami 
and  Corpora  Striata,  and  (b)  their  relations  (as  well  as  that  of 
Fibres  which  simply  issue  from,  or  go  to,  these  'great  Ganglia) 
with  different  parts  of  the  cortex  of  the  Cerebral  Hemispheres; 
(3)  The  microscopic  anatomy  of  the  Cerebral  Convolutions ;  (4)  The 
relations  of  the  Commissures  of  the  Brain,  including  (a)  those 
connecting  similar  regions  in  the  two  Hemispheres,  (6)  those  con- 
necting different  regions  in  the  same  Hemisphere,  and  (c)  those 
bringing  the  Cerebellum  into  relation  with  the  Cerebral  Hemi- 
spheres; (5)  The  general  structure  of  the  Cerebellum  and  its 
relations  with  other  parts;  (6)  The  microscopic  anatomy  of  the 
Cortex  of  the  Cerebellum ;  (7)  The  central  connections  of  the 
various  Cranial  ISTerves;  (8)  The  relations  of  the  Visceral  System 
of  JSTerves  with  the  Brain. 


1.— Internal  Topography  of  the  Human  Brain. 

The  nature  of  the  '  lateral '  and  other  Ventricles,  and 
the  relations  of  all  of  them,  except  the  fifth,  to  the  origin- 
ally wide  canal  of  the  primitive  Cerebro- Spinal  Nerve 
Tube,  has  already  been  indicated  (pp.  267,  333,  338). 

The  Lateral  Ventricles  in  the  healthy  and  well- 
developed  Human  Brain  are  comparatively  narrow 
cavities,  represented  in  the  main  by  three  spurs  or 
*  cornua.'  (Fig.  151.)  The  arrangement  of  parts  in  and 
about  these    Lateral  Ventricles  is  essentially  similar  to 


430 


THE    INTERNAL    STRUCTURE 


that  met  with  in  the  higher  Apes,  in  whom  the 
previously  much-talked  of  '  posterior  cornua '  exist,  as 
well  as  the  small  swelling  ('  hippocampus  minor  ')  on  its 

inner  side,  which  corres- 
ponds externally  with  the 
calcarine  sulcus  (see  p. 
304).  The  Corpora  Quad- 
rigemina  and  adjacent 
structures  also  present 
no  distinct  peculiarities. 
As  there  are  no  fiesh 
structures  met  with  in 
these  regions  of  the  Hu- 
man Brain,  no  special 
description  of  its  internal 
topography  is  needed, 
other  than  what  is  to  he 
gathered  from  figs.  151— 
153,  with  their  explana- 
tions. These  the  reader 
will  do  well  to  study,  and 
compare  with  figures  of 
the  same  parts  helonging 
to  some  of  the  lower 
animals(figs.  86,87,115). 
Some  few  details  con- 
cerning the  structure  of 
the  Corpora  Striata  and  Thalami  will  moreover  he  found 
in  the  next  section. 


Fig.  151.— The  Lateral  Ventricles  and  their 
Cornua,  with  Contiguous  Structures.  (After 
Sharpcy.)  The  upper  portions  of  the  Hemi- 
spheres have  been  cut  away ;  the  Fornix  (c) 
has  been  cut  across  and  reflected,  so  as  to 
show  the  'velum  interpositum  '  (d  d)  and  the 
great  veins  of  Galen  which  convey  blood  away 
from  the  central  parts  of  tbe  Brain,  including 
the  Corpora  Striata  (6)  ;  a,  e,  ff,  are  the  three 
cornua  of  the  Ventricles ;  /,  Hippocampus 
major  (to  show  which  the  brain  substance  has 
been  cut  away  still  more  on  the  right  side)  ; 
h,  Hippocampus  minor. 


2.— The   Distribution   ol  the   Fibres   Composing  the 
Cerebral  Peduncles. 

Serious  attempts  have  been  made  during  recent  years 
to  unravel  the  precise  course  of  the   different  bands  of 


Chap.  XXIIL] 


OF    THE    HUxMAN    BRAIN. 


431 


fibres  which  pass  from  the  Spinal  Cord  into  the  Brain, 
and  vice  versa.  The  laborious  investigations  of  Stilling, 
Lockhart  Clarke,  Meynert  and  others  in  regard  to  the 
intimate  structure  of  the  Medulla,  valuable  as  they  are, 
will  be  but  little  referred  to  here,  because  they  have 
revealed  details  far  too 
complex  and  technical  to 
be  now  set  forth,  and  also 
because  a  statement  of 
the  general  arrangement 
of  its  principal  parts  will 
be  all  that  is  really  need- 
ful for  the  carrying  out  of 
our  present  plan. 

The  intimate  structure 
and  distribution  of  fibres 
in  higher  parts  of  the 
Brain  is  a  study  of  no 
less  extreme  difficulty, 
w4iich  in  recent  years  has 
been  dealt  with  principally 

±.  T         Fig.  152.— Third  and  Fourth  Ventricles  of 

by     Meynert,      LuyS      and     the  Brain  exposed  by  removal  of  the  '  velum 

interpositum  '  and  further  cutting  away  of 
Cerebr^il  Hemispheres  and  portions  of  Cers- 
belhmi.  (After  Sharpey.)  a,  Corpus  stria- 
tum ;  b,  Thalamus  ;  c,  anterior  pillars  of 
Fornix ;  d,  soft  or  '  nmiddle  commissure ' 
stretching  across  third  ventricle  ;  e,  Pineal 
body;  /,  /,  Corpora  quadrigemina ;  g,  g, 
01  superior  Cerebellar  Peduncle  with  {h)  part  of 
the  'valve  of  Vieussens'  lyingbetweenthem 
and  forming  the  roof  of  (4)  the  fourth  ven- 
tricle. 


Broadbent.  Concerning 
many  points  these  ob- 
servers are  far  from  being 
an- 


in   accord   with  one 
other.       The      views 
Meynert  on  this  difficult 
subject,  have   of  late  re- 
ceived   what    they   much 

needed  in  the  way  of  re-arrangement  and  clearer  exposi- 
tion from  Professor  Huguenin  of  Zurich,  and  the  value  of 
his  work  has  been  further  enhanced  in  its  French  transla- 
tion by  the  incorporation  of  new  matter  contributed  by  its 


432 


THE    INTERNAL    STRUCTURE 


editors,  MM.  Duval  and  Keller.*  This  treatise  will'  well 
repay  careful  study  by  those  who  will  not  he  repelled  by  its 
technicalities,  and  are  capable  of  understanding  them.  It 
seems  more  than  doubtful,  however,  whether  Meynert  is 
right  in  his  general  point  of  view  as  to  the  separate 
representation  of  sensory  and  motor  channels  for  Auto- 
matic and  Voluntary  Movements  respectively.  Luys,  in 
addition  to  the  opportunity  afforded  by  his  larger 
systematic  work,f  has  again   stated  his  views  in  one  of 


Fig.  153,— Longitudinal  Vertical  Section  through  the  Left  Hemisphere,  showing 
the  Lateral  Ventricle  and  its  three  Cornua.  (Sappey,  after  Hirschfeld.)  1,  2,  intra 
and  extra  ventricular  portions  of  the  Corpus  Striatum  separated  by  (3)  a  stratum  of 
■white  fibres;  4,  junction  of  the  body  of  the  Ventricle  with  its  'anterior  cornu  ' ; 
5,  'posterior  cornu';  G,  Hippocampus  minor;  7,  descending  or  'middle  cornu'; 
8,  Hippocampus  major  covered  by  (9)  the  choroid  plexus  ;  10,  section  of  the  corpus 
callosum  ;  11,  anterior  commissure;  15,  fissure  of  Sylvius. 


the  volumes  of  this  series.  J  If  little  reference  be  made  to 
his  opinions  in  this  chapter  it  is  j)artly  for  these  reasons 
and  partly  because  the  investigations  of  Broadbent,  so  far 
as  they  have  gone,  have  been  more  especially  directed  to 
some  of  the  points  which  can  be  here  most  advantageously 

*  Anatomie  des  Centres  Nerveux,  par  Hugnenin,  Paris,  1879. 
t  Sur  le  Systeme  Nervcux  Cerebro-Spiual,  1865. 
X  Le  Cerveau  et  ses  fonctions,  1876. 


Chap.  XXIIL]  OF    THE    HUMAN    BRAIN.  4o3 

discussed — partly,  moreover,  because  his  observations  seem 
to  tbe  writer  to  have  been  conducted  with  great  care,  and 
also  to  have  been  interpreted  from  a  correct  general 
standpoint.  Thus,  though  the  investigations  of  Broadbent 
have  as  yet  only  been  published  in  abstract,*  they 
will  principally  be  cited  in  this  and  in  the  following 
sections. 

One  of  the  most  fundamental  facts  in  regard  to  the 
structural  relations  of  the  Cerebral  Hemispheres  and 
their  Peduncles,  is  that  the  left  half  of  the  Brain  is 
specially  in  connection  with  the  right  half  of  the  body, 
and  the  right  half  of  the  Brain  with  the  left  half  of  the 
body.  This  arrangement  exists  not  only  in  Man,  but  in 
Venebrates  generally  (though  with  varying  degrees  of 
completeness),  and  it  is  due  to  the  fact  that  the  'ingoing' 
fibres  to  each  Cerebral  Hemisphere  come  from,  whilst  its 
*  outgoing '  fibres  are  distributed  to,  the  opposite  half  of 
the  body. 

Speaking  in  general  terms,  it  may  be  said  that  the 
'ingoing'  fibres  which  enter  the  Cord  and  Medulla  on  either 
side  throughout  their  whole  length,  soon  cross  over,  as 
Brown- Sequard  has  shown,  to  the  opposite  side  of  these 
centres ;  and  that  they  thence  follow  an  ascending  course 
towards — though  they  do  not  necessarily  go  as  far  as — 
the  Cerebral  Hemisphere  of  the  same  side.  Similarly, 
an  important  section  at  least  of  the  '  outgoing '  or  motor 
fibres,  viz.,  those  forming  part  of  the  '  anterior  pyramids  ', 
decussate  with  their  fellows  in  the  Medulla,  so  as  to  pass 
over  to  the  opposite  '  lateral  column  '  of  the  Cord.  Thus, 
even  allowing  for  the  fact  that  some  of  the  Cranial  Motor 
Nerves  decussate  by  themselves  higher  up,  in   the  sub- 

*  "  The  Structure  of  the  Cerebral  Hemisphere,"  Journal  of 
Mental  Science,  1870 ;  aud  also  "The  Construction  of  a  iSI'ervous 
System,"  JBiit.  Med.  Joiirn.,  March  &  April,  1876. 


434 


THE    INTERNAL    STRUCTURE 


stance  of  the  'pons  Varolii '  (fig.  154),  the  sites  in  which 
decussation  of  motor  channels  takes  place,  are  altogether 

limited  in  area  when  com- 
pared with  what  obtains  for 
sensor}^  channels. 

The  longitudinal  fibres  of 
the  Spinal  Cord  are  in  the 
main  divisible  (if  we  exclude 
those  specially  in  relation 
with  the  Cerebellum)  into 
three  categories,  viz.,  (1) 
fibres  transmitting  '  ingoing  ' 
currents  towards  the  Brain  ; 

(2)  fibres  which  transmit 
'  outgoing  '     currents  ;     and 

(3)  fibres  of  a  '  commissural ' 
order,  serving  to  connect 
separate  groups  of  cells  or 
centres  in  different  parts  of 
the  Spinal  Cord  itself,  or  in 
the  Spinal  Cord  and  Me- 
dulla. 

The  Spinal  Cord  being, 
moreover,  a  bilaterally  sym- 
metrical organ,  the  groups 
of  cells  above  referred  to 
are  similarly  represented  in 
each  half  of  it  (fig.  19)  ;  and 
the  similar  Motor  and  Sen- 
sory regions  of  these  two  halves  of  the  Cord  and  Medulla 
are  to  a  considerable  extent  brought  into  structural  relation 
with  one  another  by  means  of  numerous  transverse  '  com- 
missural '  fibres.  ' 

The  first  two  sets  of  longitudinal  fibres,  above  referred 


Fig.  154.  —  Diagram  illustrating  the 
place  and  mode  of  '  decussation '  of 
Motor  Fibres  in  the  Medulla  and  in  the 
Pons.  (i3roadbent.)  B,  B',  two  sets  of 
nuclei  of  brachial  plexus,  not  con- 
nected by  transverse  commissures  ; 
O,  O',  two  sets  of  oculo- motor  nuclei  in 
Pons,  freely  connected  with  one  another 
by  transverse  commissural  fibres. 
S,  S',  motor  fibres  from  Corpus  Striatum. 


Chap.  XXIir.] 


OF    THE    HUMAN    BRAIN. 


435 


lo,  pass   on  each  side  in  compact  columns  through  the 
MeduUa,  and  through  that   continuation  of  it  which  is 
crossed      by     the 
'middle  peduncles' 
of  the  Cerebellum 
(viz.,     the    pons 
Varolii).    Beyond 
this    point,    both 
sets    of  fibres   of 
the    one    side  di- 
verge from   those 
of  the  other  (fig. 
154)     so    as 
form      what 
known      as 
'  Cerebral 
duncles.'     These 
parts  are  seen  on 
the  under  surface 
of  the  brain,  es- 
pecially when  the 
tips  of  the  Tem- 
poral   Lobes    are 
drawn      outwards 
or    removed    (fig. 
155,  re).      Each 
Peduncle        soon 
disappears  within 
the  corresponding 
Cerebral      Hemi- 
sphere, and  then 
its  future  course, 

or  that  of  its  constituent  fibres,  can  only  be  made  out  by 
the  most  careful  dissections.     It  spreads  out  rapidly  into 


Fig.  155. — On  right  side  shows  plane  of  fibres  under- 
lying superficial  convolutions  on  interior  aspect  of  Tem- 
poral Lobe,  and  forming  the  floor  of  Descending  Cornu. 
The  Cornu  has  been  opened  anteriorly,  and  fibres  (s  x) 
from  the  apex  of  the  lobe  to  the  extra-ventricular  Cor- 
pus striatum  are  seen.  On  the  left  side  of  figure,  the 
dissection  has  been  carried  further,  and  the  Optic  Tract 
has  been  removed,  rr,  Crura  Cerebri,  re,  Crusta.  rt. 
Fibres  of  Tegmentum  (and  from  Thalamus)  turning 
round  anterior  edge  of  Crusta.  th,  Tail  of  Thalamus, 
turning  round  posterior  edge  of  Crusta,  forming  '  Collar 
of  Crus,'  and  distributing  fibres  to  Sylvian  margin  of 
Temporal  Lobe,  th'  and  sx',  Fibres  from  Thalamus  and 
extra-ventricular  Corpus  Striatum  respectively  to  Oc- 
cipital extremity  of  Hemisphere.  The  longitudin,il 
fibres  not  indicated  by  letters  belong  chiefly  to  the  sy.-i- 
tem  of  the  Gyrus  Uncinatus.     (Broadbent.) 


436  THE    INTERNAL    STRUCTURE 

a  fan-like  expansion,  the  '  corona  racliata,'  the  edges  of 
the  fan  being  directed,  as  Broadbent  says,  "  forwards  and 
backwards,  the  surfaces  inward  and  outward,  but  sloping 
outwards,  so  that  the  outer  surface  looks  downwards,  and 
is  concave,  the  inner  looks  upwards,  and  is  convex." 

On  cutting  across  one  of  the  Peduncles  in  front  of  the 
Pons  it  is  found  to  be  separated  into  two  layers  of  fibres 
by  a  grayish  black  streak  of  ganglionic  tissue,  known  as 
the  '  locus  niger.'*  Looked  at  from  the  under  surface,  the 
most  superficial  stratum  (that  is,  the  under  and  anterior 
stratum  in  the  natural  position  of  the  Brain)  is  known  as 
the  *  Crusta^^  and  is  made  up  of  wdiite  fibres.  It  doubt- 
less consists  of  the  bulk  of  the  outgoing  fibres,  w^hich 
lower  down  are  clustered  together  into  the  *  anterior 
pyramids  '  of  the  Medulla,  together  with  other  fibres 
terminating  in  *  motor '  cell-groups  in  the  Pons  and 
Medulla.  Mixed  with  these,  in  all  probability,  are  fibres 
which  suffice  to  connect  the  Corpus  Striatum  with  the 
Cerebellum  through  the  intermediation  of  its  *  middle 
peduncles.'  The  deeper  stratum  (that  is  the  upper  and 
posterior  parts  of  the  Peduncles  in  the  natural  position 
of  the  Brain),  constituting  what  is  known  as  the  *  Teg- 
mentum,^ is  not  so  white  in  colour,  and  seems  to  be 
mainly  composed  of  *  ingoing '  fibres  derived  from  the 
Cord  and  Medulla. 

*'  The  Crusta  and  Tegmentum,"  Broadbent  says,  "can 
be  separated  from  each  other  for  some  distance  upwards, 
as  they  spread  out  to  form  the  fan-like  expansion  spoken 
of;  but  before  they  emerge  from  the  central  ganglia  the 
fibres  of  one  sink  in  between  those  of  the  other,  and  they 
become  mixed  together,  so  as  to  be  no  longer  distinguish- 
able." 

*  Its  colour  being  due  to  the  abundance  of  pioment  granules 


contained  within  the  large  nerve  cells  of  this  region. 


Chap.  XXIII  ] 


OF    THE    HUMAN    BRAIN. 


437 


a.    Halation  of  the   Cerebral  Peduncles   to  the  Central 
Ganglia  :   Thalami  and  Corpora  Striata, — According  to 


Fig.  156. — Central  Ganglia  of  the  Brain,  together  with  the  Cerebellum  and  its 
Superior  Peduncles.  (Sappey,  after  Hirschfeld.)  1,  Corpora  quadrigemina ; 
2,  Valve  of  Vieussens ;  3,  superior  Cerebellar  Peduncles ;  4,  upper  part  of  the 
middle  Cerebellar  Peduncles  ;  5,  upper  part  of  the  Cerebral  Peduncles  ;  6,  lateral 
groove  of  the  isthmus;  7,  ribbon  of  Reil ;  8,  cord  extending  from  the  'testis'  to 
the  internal  'geniculate  body';  9,  column  of  the  Valve  of  Vieussens;  10,  grey 
lamella  of  the  same  ;  11,  posterior  fibres  of  the  triangular  bundle  of  the  isthmus  ; 
12,  upper  fibres  of  middle  Cerebellar  Peduncles  ;  13,  white  centre  of  the  Cerebellum  ; 
14,  grey  rhomboidal  nucleus  of  Cerebellum  ;  15,  '  posterior  commissure  '  of  Cerebrum  ; 
16,  peduncles  of  the  'Pineal  body' ;  17,  'Pineal  body'  turned  forwards  so  as  to  show 
last  two  structures  ;  18,  posterior  tubercles  of  the  Thalami  ;  19,  anterior  tubercles  of 
same ;  20,  Tenia  semicircularis  ;  21,  veins  of  the  Corpus  Striatum  ;  22,  anterior 
pillars  of  the  Fornix,  between  which  the  '  anterior  commissure  '  is  seen ;  23,  Corpus 
Striatum  ;  24,  Septum  Lucidum  and  '  fifth  ventricle.' 


the  above-quoted  anatomist,   "  The  Thalamus  and    Cor 


438  THE    INTERNAL    STRUCTURE 

pus  Striatum  may  be  said  to  sit  astride  the  posterior 
and  anterior  edge  respectively,  of  the  fan  formed  by  the 
Crus  as  it  expands,  each  having  an  intra-ventricular  and 
an  extra-ventricular  division.  The  Thalamus  is  much  the 
smaller  of  the  two  ganglia,  and  may  be  said  to  be 
embraced  by  the  Corpus  Striatum,  which  is  also  on  a 
rather  higher  level.  Both  in  structure  and  in  their  relations 
with  the  crus  on  the  one  hand,  and  the  convolutions  of 
the  hemisphere  on  the  other,  there  is  a  remarkable  con- 
trast between  the  Thalamus  and  the  Corpus  Striatum." 

The  Thalamus  consists  of  an  admixture  of  fibres  and 
grey  matter,  and  has  a  whitish  colour  on  the  surface — 
distinctly  contrasting  with  the  greyer  tint  of  the  Corpus 
Striatum. 

By  far  the  larger  part  of  the  Thalamus  seems*  to  pro- 
ject into  the  '  lateral  ventricle  '  as  it  "  rests  upon  the  teg- 
mentum of  the  crus,  from  wliich  it  can  be  raised  from 
behind,  forwards  and  upwards,  the  diverging  fibres  of 
this  part  of  the  crus  appearing  to  pass  onwards  beneath 
the  ganglion  without  ending  in  it."  But  as  Broadbent 
further  remarks : — "  It  is  possible  that  communication, 
by  means  of  cell  processes,  exists  between  the  radiating 
fibres  and  the  overlying  ganglion,  bringing  them  into  a 
relation  equivalent  to  the  direct  termination  of  fibres 
and  cells." 

The  portion  of  the  Thalamus  that  actually  has  the  ap- 
pearance of  lying  outside  the  ventricle,  consists  ''  only 
of  a  prolongation  from  the  body  of  the  ganglion  which 
bends  round  the  posterior  edge  of  the  crus,  and  curves 
forwards  in  the  roof  of  the  descending  cornu  of  the 
lateral  ventricle,  becoming  pointed  anteriorly." 

The  Corpus  Striatum  is  divided  into  two  distinct 
parts  by  the  radiating  fibres  of  the  Crus  which  pass 
*  See  pp.  269,  270  note,  aud  fig.  122. 


Chap.  XXITL] 


OF    THE    HUMAN    BRAIN. 


439 


tlirougli  it.  ''  The  intra-ventricular  portion  consists  of  a 
deposit  or  bed  of  soft  grey  matter,  not  intermixed  with 
distinct  fibres  visible  to  the  naked  eye,  thicker  and  wider 
anteriorly  in  the  anterior  cornu  of  the  ventricle — narrow- 
ing to  a  point  posteriorly.  It  rests  upon  the  radiating 
fibres  of  the  tegmentum  and  thalamus  which  pass  on- 


ENS 

'  Fia.  157.— Transverse  section  of  the  Cerebrum,  just  behind  Infuudibulum. 
S  V,  Intra-ventricular,  and  SX,  Extra-ventricular  Corijus  Striatum.  T h,  Thalamus, 
re,  Crusta,  andrt,  Tegmentum  of  Crus  Cerebri;  R,  radiating  expansion  of  white 
fibres  ('corona  radiata');  re.  rt,  and  R  together  form  what  has  been  called  the 
'internal  capsule'  of  the  Lenticular  Nucleus.  Cx,  'external  capsule'  (including 
the  Claustrum);  C,  Corpus  Callosum ;  FS',  Fissure  of  Sylvius;  LMG,  Longitudinal 

Marginal  Gyrus.    S  M  G,   S  M  G',    Sylvian  Marginal  Gyrus  ; ,  indicate  lines  of 

derivation  of  fibres  of  Corpus  Striatum  ;....,  Fibres  of  distribution  of  Thalamus. 
(Broadbent.) 

wards  beneath  it  to  the  hemisphere  proper,"  Between 
the  bundles  of  radiating  fibres  this  upper  and  anterior 
portion  is  continuous  with  the  lower  and  outer  '  extra- 
ventricular  '  portion  of  the  Corpus  Striatum,  which  is  more 
bulky  than  the  part  already  described,  though  it  is,  like  it, 
also  larger  in  front  than  behind.  It  is  a  somewhat  pear- 
shaped   mass   of    soft    grey   matter,  bounded    above    and 


140  THE    INTERNAL    STRUCTURE 

within  by  the  radiating  fibres  of  the  Cms  {'  internal 
capsule ')  ;  and  externally  (fig.  157,  C  x)  by  a  thin  stratum 
of  fibres  ('  external  capsule  ')  issuing  from  its  interior  for 
distribution  to  various  regions  of  the  Hemisphere,  though 
forming  in  the  first  part  of  their  course  to  the  convolu- 
tions (together  with  some  other  fibres  from  the  '  fasiculus 
uncinatus '  to  be  hereafter  described)  an  outer  wall, 
serving  to  separate  this  inferior  portion  of  the  Corpus 
Striatum  from  the  immediately  adjacent  convolutions  of 
the  '  island  of  Reil ' — the  situation  of  which  has  been 
already  defined  (see  pp.  301,  341,  381). 

b.  Relations  of  fibres  composing  the  Cerebral  Peduncles 
as  well  as  of  fibres  issuing  from  or  going  to  the  Central 
Ganglia,  tvith  different  Convolutions  of  the  Cerebral  Hemi- 
spheres.— It  is  easily  to  be  demonstrated,  according  to 
Broadbent,  that  "  fibres  of  the  crus  in  large  numbers  pass 
uninterruptedly  through  or  by  the  Central  Ganglia  to  the 
Convolutions."  And  he  adds,  "In  the  case  of  the  fibres 
of  the  posterior  edge  of  the  Crus  there  is  scarcely  room 
for  error  on  this  point,  as  they  do  not  come  at  all  into 
relation  with  grey  matter  on  their  way."* 

Other  fibres  of  both  '  tegment'  and  '  crust,'  seem  to  end 
in  or  take  their  origin  from  the  grey  matter  of  the  Corpus 
Striatum,  though  Broadbent  is  inclined  to  believe  that 
*'no  fibres  of  either  division  end  in  the  Thalamus. "f 

From  both  Thalamus  and  Corpus  Striatum,  however, 
many  independent  fibres  appear  to  issue,  which  serve  to 
connect  these  ganglia  with  Convolutions  in  different  parts 

*  Some  of  these  fibres  which  merely  pass  through  or  by  the 
Central  GangHa  may,  as  certain  anatomists  suppose,  serve  to  con- 
nect the  Cerebral  Cortex  with  the  Cerebelhnu,  by  way  of  its 
*  middle  peduncles.' 

t  This  seems  a  very  doubtful  proposition.  The  anatomical  rela- 
tions of  the  Thalami  are,  however,  as  yet,  as  uncertain  as  are  their 
functions. 


Chap.  XXIII.]  OF    THE    HUMAN    BRAIN.  441 

of  the  Hemispheres.*  These  two  sets  of  fibres  do  not 
proceed  to  the  grey  matter  of  the  Convolutions  separately, 
but  are  for  the  most  part  inextricably  mixed  with  those 
fibres  of  the  Peduncle  (above  referred  to)  which  pass  unin- 
terruptedly through  the  Central  Ganglia.  Outside  these 
bodies,  moreover,  all  three  sets  of  fibres  become  further 
intermixed  with  those  of  the  great  transverse  commissure 
between  the  hemispheres — the  Corpus  Callosum. 

But  some  further  account  must  be  given  of  the  course 
of  these  three  sets  of  fibres — answering  to  the  *  projection 
system  '  of  Meynert.  Their  mode  of  distribution  is  neces- 
sarily a  matter  of  great  importance,  if  any  coherent  notions 
are  to  be  formed  even  as  to  the  simpler  modes  of  action 
of  the  Brain.  The  reader  ought,  therefore,  carefully  to 
study  the  particulars  given  below,  making,  as  he  proceeds, 
frequent  references  to  those  figures  in  which  the  relative 
position  of  the  Convolutions  alluded  to  may  be  seen.  The 
substance  of  Broadbent's  description  is  subjoined. f 

The  fibres  of  Cms,  Thalamus,  and  Corpus  Striatum  always  run, 
more  or  less,  in  company  with  one  another  to  the  same  parts.  For 
brevity,  they  may  be  spoken  of  as  '  radiating  '  fibres. 

(But,  wherever  '  radiating  '  fibres  go,  thither  also  go  fibres  of  Cor- 
pus Callosum — though  not  necessarily  in  the  same  proportion.  Thus 
it  happens,  that  those  Convolutions  in  which  '  radiating '  fibres  ter- 
minate or  commence,  are  also  bilaterally  associated  through  the 
Corpus  Callosum,  and  are  thereby  fitted  for  conjoint  activity.) 

These  '  radiating '  and  '  callosal '  fibres  are  not  distributed 
equally  to  all  the  Convolutions.  Many  of  the  latter  do  not  receive 
a  smgle  fibre  from  Crus,  Thalamus,  Corpus  Striatum,  or  Corpus 
Callosum,  but  have  only  an  indirect  communication  with  the  ceu- 

■5^  Broadbent  says  ("  Journ.  of  Ment.  Science,"  Ap.  1870,  p.  9) : — 
"A  comparison  again,  of  the  sectional  area  of  the  fibres  thus  seen 
issuing  from  the  Central  Ganglia  with  the  area  of  the  Crus  as  it 
emerges  from  under  the  Pons,  will  show  that  the  ascending  fibres 
have  been  largely  reinforced  by  additions  from  the  Ganglia." 

t  "  Brit.  Med.  Journ.,"  April  8,  1876,  p.  433. 


442  THE    INTERNAL    STRUCTURE 

tral  ganglia  or  great  commissure,  by  means  of  looped  fibres  pass- 
ing to  them  from  Convolutions  wbicb  are  directly  connected  with 
'  radiating  '  and  '  callosal '  fibres. 

The  following  summary  statements  made  by  Broad- 
bent  *  in  regard  to  the  exact  distribution  of  the  *  radiat- 
ing '  and  '  callosal '  fibres,  and  as  to  the  Convolutions  to 
which  they  do  not  proceed,  will  be  found  to  contain  im- 
portant particulars. 

"The  convolutions  to  v^hich  the  radiating  and  callosal  fibres  go, 
are  chiefiy  those  along  the  margins  of  the  Hemisphere:  the  margin 
of  the  great  longitudinal  fissure  on  one  hand;  the  margins,  supe- 
rior and  inferior,  of  the  Sylvian  fissure  on  the  other,  continued 
forwards  by  the  inferior  frontal,  backwards  by  the  inferior  occipi- 
tal gyri,  to  the  frontal  and  occipital  extremities  of  the  Hemisphere 
respectively,  which  are  well  supplied;  the  free  margin,  again, 
formed  by  the  hippocampus  major.  To  these  must  be  added  the 
ascending  convolutions  on  each  side  of  the  sulcus  of  Rolando, 
named  ascending  frontal  and  parietal,  or  sojnetimes  anterior  and 
posterior  ascending  parietal;  and  perhaps  the  second  frontal. 
Callosal  fibres  pass  more  abundantly  to  the  margin  of  the  longi- 
tudinal fissure;  radiating  fibres  to  the  Sylvian  border  of  the 
hemisphere." 

The  Convolutions,  on  the  other  hand,  which  receive  no  '  radiating 
or  '  callosal '  fibres  are  *'  all  those  on  the  fiat  internal  surface  of  the 
hemisphere,  those  on  the  inferior  aspect  of  the  temporo-s])henoidal 
lobe  and  orbital  lobule,  the  convolutions  of  the  island  of  Reil,  and 
those  on  the  convexity  of  the  occipital  and  parietal  lobes  not  near 
either  margin,  as  iar  forwards  as  the  ascending  convolution  which 
hes  behind  the  sulcus  of  llolando."  Broadbent  adds: — "It  may 
seem  less  strange  that  there  are  convolutions  without  central  or 
callosal  fibres,  if  we  recollect  that  nowhere  do  these  fibres  2)ass  to 
the  grey  matter  within  the  sulci,  hut  only  to  the  crests  of  the  gyri, 
80  that  hy  far  the  greater  pay-t  of  the  cortex  is  ivithout  thc7n." 

The  same  investigator  also  says  : — "  The  statement  that 
the  fibres  of  the   Cms,  Thalamus,  Corpus  Striatum,  and 
Corpus  Callosum  always  go  together  to  the  same  convolu- 
tion, may  appear   to   go  beyond   what   is   demonstrable, 
*  Loc.  cit.  p.  433. 


Chap.  XXIII.]  OF    THE    HUMAN    BRAIN.  443 

seeirg  that  they  are  so  mixed  up  as  not  to  be  traceable 
separately ;  and  it  is  not  quite  what  might  have  been 
expected."  At  certain  parts,  however,  as  Broadbent 
points  out,  a  triple  if  not  a  quadruple  mode  of  supply  is 
easily  shown,  and  in  illustration  he  cites  the  following 
facts  *  : — 

The  fibres  which  pass  to  the  tip  of  the  Occipital  Lobe  from 
three  of  these  sources,  viz.,  Corpus  Striatum,  Thalamus,  and  Cor- 
pus Callosum,  form  distinct  masses  at  their  point  of  departure, 
and  only  blend  with  one  another  near  their  termination  in  the 
Convolutions 

A  similarly-independent  communication  exists  with  certain 
Convolutions  so  situated,  that  in  order  to  reach  them  fibres  of 
one  or  other  of  the  three  orders  in  question,  have  to  take  an  extra- 
ordinary course.  Thus,  the  Convolutions  of  the  anterior  extremity 
and  of  the  upper  margin  of  the  Temporal  Lobe,  are  directly 
connected  with  (1)  the  adjacent  Corpus  Striatum,  by  fibres  which 
stretch  across  the  fissure  of  Sylvius;  (2)  the  fibres  of  the  Thala- 
mus, to  the  same  convolutions,  are  given  off  from  that  part  of  it 
which  bends  round  in  the  roof  the  descending  cornu  of  the  ven- 
tricle, whence  these  afferent  fibres  diffuse  themselves  so  as  to  reach 
the  Convolutions  in  the  regions  specified;  whilst  (3)  the  '  commis- 
sural '  fibres  for  these  same  parts  are  chiefly  represented  by  those 
of  the  Anterior  Commissure, — which  from  a  functional  point  of 
view,  is  to  be  regarded  as  a  detached  portion  of  the  great  trans- 
verse commissure  or  Corpus  Callosum.  The  '  commissural '  fibres 
are,  however,  also  represented  by  certain  anterior  fibres  of  the 
Corpus  Callosum  itself,  which,  near  the  anterior  perforated  space, 
cross  to  the  apex  of  the  Temporal  Lobe. 

Even  more  extraordinary  is  the  separate  course  taken  by  those 
of  the  three  sets  of  fibres  to  which  we  are  referring  that  happen 
to  be  in  relation  with  the  Hippocampus  Major.  This  structure, 
Broadbent  says, — "is  in  communication  with  the  Corpus  Striatum, 
at  its  uncinate  exti-emity ;  with  its  fellow  in  the  opposite  hemi- 
sphere by  the  reflected  part  of  the  splenium  corporis  callosi, 
which  I  have  called  the  commissure  of  the  hippocampi ;  f  but  its 

"^  Loc.  cit.  p.  433. 

t  Corresponding  with  the  '  psalterial  fibres '  already  referred  to 
in  a  previous  chapt>  r  (pp.  273,  274). 


444  THE    INTERNAL    STRUCTURE 

situation  on  the  outer  side  of  the  great  transverse  fissure  of  the 
braiti  seems  to  cut  it  off  from  the  Thalamus.  The  connection, 
however,  is  effected  by  ihe  fibres  of  the  Foi-nix,  which,  as  is  well 
known,  arise  from  the  Thalamus,  make  a  figure-of-8  turn  in  the 
corpora  albicantia,  then  take  the  circuit  upwards,  and  then  back- 
wards, described  by  this  body  [i.e.,  the  Fornix],  and  pass  to  the 
Hippocamj)us  in  the  t^uia." 


3.— The  Microscopic  Anatomy  of  the  Cerebral  Con- 
volutions. 

It  has  been  already  stated  that  the  Convolutions  differ 
much  as  regards  their  relations  to  one  another,  to  the 
Central  Ganglia,  and  to  the  fibres  of  the  Crus. 

All  the  Convolutions,  however,  present  certain  common 
characters.  When  a  section  is  made  through  either  one 
of  them  in  a  direction  transverse  to  its  long  axis,  a  stem 
or  projection  of  white  matter  is  seen  continuous  with  the 
*  white  substance  '  of  the  hemisphere.  Externa]  to  this 
white  substance,  a  superficial  layer  of  Grey  Matter  exists, 
having  an  average  thickness  of  about  one-fourth  of  an 
inch,  which  is  continuous  over  the  whole  external  surface 
of  the  Hemisphere — since  it  lines  the  *  sulci '  as  well  as 
the  Convolutions  (fig.  158). 

This  layer  of  cortical  Grey  Matter,  has  a  greater  depth 
over  the  frontal  and  parietal  than  over  the  occipital  con- 
volutions. Its  specific  gravity,  moreover,  varies  in  these 
situations,  being  often  three  or  four  degrees  higher  in  the 
occipital  than  it  is  in  the  frontal  region  (10B2  :  1028) — 
whilst  that  of  the  parietal  convolutions  is  more  or  less 
intermediate. 

In  the  grey  matter  of  the  Occipital  Lobe,  especially  that 
of  the  Convolutions  of  its  inner  and  inferior  surface,  a  dis- 
tinct lamination  is  generally  very  apparent,  either  to  the 
naked  eye  or   with  the  aid  of  a  pocket  lens.     These  con- 


Chap.  XXIII.  ] 


OF    THE    HUMAN    BRAIN. 


445 


volutions  were  examined  and  originally  described  by 
Lockhart  Clarke  =^^  in   1863. 

He  observed  the  divergence  of  bandies  of  fibres  in  a 
fan-like  manner  from  the  central  stem  of  white  substance, 
and  their  passage 
between  long  ver- 
tical groups  of 
nerve-cells  situ- 
ated in  the  deeper 
grey  layers  (fig. 
159).  Some  of 
the  fibres,  he  be- 
lieved, were  con- 
tinuous with  the 
processes  of  the 
cells,  whilst  others 
turned  round  and 
pursued  a  hori- 
zontal course 
(either  in  a  trans- 
verse or  in  a  lon- 
gitudinal direc-  pj^^  ISS.— Transverse  section  thrmigh  anterior  part  of 
tion).  The  bun-  ^®ft  Frontal  Lobe,  showing  shape  of  Convohxtioi.s  and 
-.-  e     Xil  •        relative  thickness    of   Grey    Matter,     a,    Third   frontal 

ClleS     01      nbreS     m     convolution,  a  magnified  section  of  which  is  shown  in 

this   manner    be-   the  next  figure. 

come  reduced  in  size,  and  at  the  same  time  the  com- 
ponent fibres  become  finer  as  they  approach  the  surface — 
apparently  in  consequence  of  the  branches  which  they  give 
off,  in  their  course,  to  contiguous  nerve  cells.  When  they 
arrive  at  the  third  layer  from  the  surface,  they  ''  are 
reduced  to  the  finest  dimensions,  and  form  a  close  net- 
work with  which  the  nuclei  and  cells  are  in  connection." 
The  two  layers  superficial  to  this  are  paler  in  colour  and 

■*  Proceed,  of  Royal  Society,  vol.  xii.  p.  716. 
20 


446 


THE    INTERNAL    STRUCTURE 


y 


are  composed  for  the  most  part  of  an  extremely  delicate 
reticulum  of  fibres  (probably  most  akin 
to  the  'neuroglia'),  that  composing  the 
outermost  layer  being  in  direct  con- 
tinuity with  the  thin  and  very  vascular 
membrane  (the  '  pia  mater ')  which 
covers  the  whole  surface  of  the  Brain 
and  dips  down  between  the  sulci. 

The  fibres  of  the  central  white  stem 
itself  are  crossed  transversely  and  ob- 
liquely by  a  variable  number  of  other 
fibres,  generally  most  numerous  near 
its  base,  where,  according  to  Lockhart 
Clarke,  they  cross  one  another  in  all 
directions.  These,  he  thinks,  probably 
consist,  for  the  most  part,  of  '  com- 
missural fibres,'  such  as  will  be  de- 
scribed in  the  next  section. 

Other  investigators  have  since  exa- 
mined the  structure  of  the  Grey  Matter 
in  several  Convolutions  situated  in  dif- 
ferent parts  of  the  Hemisphere.  Al- 
though difterences  of  detail  exist,  there 
is  nevertheless  considerable  uniformity 
in  the  type  of  structure  met  with.  Over 
much  of  the  Frontal  and  Parietal  Lobes, 
[^  Meynert  describes  the  Grey  Matter  as 
divisible,  not  so  much  by  ordinary  sight 
as  by  the  microscopic  characters  of  its 
constituents,  into  five  layers  or  '  la- 
mina).' He  gives  a  figure  of  the  arrange- 

FiG.  159.— Section  through  one  of  the  Folds  of  the  Third  Frontal  Convolution  of 
Man.  Magnified  Go  diameter-".  (Ferrier,  after  Meynert.)  1.  Layer  of  small  scattered 
corjiusclfs,  principally  belonging  to  the  'neuroglia';  2,  layer  of  close-set  small 
pyramidal  cells ;  3,  layer  of  large  jiyramidal  celb  ;  4,  layer  of  small  close-set  irregu- 
larly shaped  corpuscles  (this  lamina  in  s<  me  regions  is  occupied  l)y  'giant'  cells); 
5,  layer  of  spindle-shaped  corpuscles  :  vi   white  or  medullary  lamina. 


Chap.  XXIIL] 


OF    THE    HUMAN    BRAIN, 


447 


ment  of  the  constituents  of  these  layers,  as  seen  in  a 
section  through  the 
'  third  frontal '  con- 
volution (fig.  159). 
Quite  recently, 
moreover,  Bevan 
Lewis  and  H.Clarke 
have  described  a 
very  similar  arrange- 
ment of  nerve  ele- 
ments in  the  *  as- 
cending frontal'  and 
other  adjacent  Con- 
volutions. Their  pa- 
per is  accompanied 
by  excellent  illus- 
trations.* 

They  give  the  follow- 
ing description  of  the 
five  layers  of  the  *  as- 
cending frontal '  —  be- 
ginning with  the  most 
superficial.  The  first 
is  a  delicate  friable  stra- 
tum containing  no  real 
nerve  elements.  It  is 
made  up  of  the  usual 
network  of  'neuroglia' 
with  finely  granular 
matrix,  in  which  are 
distributed  numerous 
small        nuclei        and 

Fig.  160.— Large  Pyramidal  Cell,  with  its  processes,  from  fourth  layer  of  Cortical 
Grey  Matter  -  so-called  'Giant  Cell.'  (Charcot.)  a,  Body  of  the  Cell  tapering  away 
into  a  branched  pyramidal  prolongation  ;  h,  Its  basal  prolongation  which  come  into 
relation  with  (c),  the  white  fibres  of  the  Convolution  (highly  magnified). 

*  Proceed,  of  Royal  Society,  1878,  p.  38. 


448  THE    INTERNAL    STRUCTURE 

branched  connective  tissue  cells.  The  second  layer  has  abont  the 
Bame  depth  as  the  first ;  to  the  naked  eye  it  is  api>arent  as  a  reddish- 
grey  band  abruptly  marked  oiF  from  the  pale  layer  beneath  it.  On 
microscopic  examination  it  is  found  to  consist  "  of  a  series  of 
closely  aggregated  pyramidal  and  oval  cells  of  small  size,  whose 
apical  processes  are  arranged  radially  to  the  surface  of  the  cortex. 
[Numerous  other  processes  arise  from  the  basal  angles,  and  radiate 
outwards  and  downwards  from  the  cell,  including  an  extensive  area 
in  their  distribution."  Each  of  these  cells  contains  a  large  nucleus 
of  round  or  pyramidal  form.  The  third  layer  is  about  three  times 
as  broad  as  the  last  and  contains  nerve  elements  of  precisely  the 
same  kind  except  that  they  are  larger  and  not  nearly  so  closely 
packed.  The  cells  seem  uniformly  to  increase  in  size  from  above 
downwards,  and  in  the  lower  part  of  this  stratum  they  are  two  or 
three  times  as  large  as  those  of  the  second  layer.  This  statement 
is,  however,  subject  to  the  qualification  that  some  smaller  cells  exist 
throughout,  interspered  amongst  those  of  larger  size.  The  fourth 
layer  is  not  radically  different  from  the  last.  It  has  only  about 
one-third  of  its  depth,  and  differs,  moreover,  by  reason  of  the  great 
increase  in  the  size  of  its  cells — otherwise  similar  in  type.  In 
consequence  of  their  considerably  superior  size  these  cells  appear 
to  be  more  closely  packed.  They  are  on  an  average  about  three 
times  as  long  and  broad  as  those  of  the  third  layer.  Interspersed 
between  them  are  a  number  of  small  angular  cells:  and  in  certain 
portions  of  this  'frontal  convolution'  the  small  cells  alone  exist  as 
representatives  of  the  fourth  layer — the  above  described  large,  or 
so-called  '  giant  cells,'  being,  in  these  parts,  wholly  absent.  The 
fifth  layer  is  again  much  broader  than  the  fourth.  It  contains 
irregularly  fusiform  or  spindle-shaped  cells  of  a  smaller  and  pretty 
uniform  size,  often  arranged  in  irregular  columns  owing  to  the 
interposition  of  the  bundles  of  medullary  fibres  which  ascend  from 
the  subjacent  white  matter. 

More  recent  observations  still*  have  shown,  (1)  that  in  many 
other  portions  of  the  Cerebral  Hemispheres  a  six-  rather  than  a 
five-laminated  Cortex  is  found  —  the  additional  stratum  in  the 
six-laminated  regions  being  produced  by  the  interposition,  between 
the  above  described  '  third'  and  '  fourth  '  layers,  of  one  containing 
"small  pyramidal  and  angular  cells":  (2)  that  the  five-laminated 

*  See  Bevan  Lewis,  "  On  the  Comparative  Structure  of  the 
Cortex  Cerebri,"  Proceed,  of  Royal  Soc,  Jane,  1879,  p.  234. 


Chap.  XXIIL]  OF    THE    HUMAN    BRAIN.  449 

type  of  Cortex  is  most  distinct  in  those  parts  of  tlie  frontal  and 
parietal  convolutions  which  constitute  the  excitable  or  so-called 

•  motor  area  '  of  Ferrier  (see  p.  575),  thoncrh  in  by  far  the  largest 
l^art  of  the  Hemispheres  the  convolutions  have  rather  a  six- 
laminated  type  :  (3)  that  in  the  five-lamitiated  regions  the  so- 
called  'giant-cells'  of  the  fourth  layer  have  generally  a  grouped  ov 
clustered  arrangement,  owing  to  these  bodies  existing  in  irregular 
aggregations  (the  'nests  *  of  Betz) ;  the  principal  exception  to  this 
lying  in  the  fact  that  at  the  bottom  of  the  '  sulci '  (where  the 
grey  layer  has  also  less  depth  than  at  the  summit  and  sides  of 
the  Convolutions),  even  in  these  regions,  such  large  cells  are  dis- 
posed in  a  regular  but  solitary  manner,  so  that  in  vertical  sections 
they  appear  to  be  ranged  in  linear  series  :  (4)  that  in  the  much 
more  extensive  six-laminated  areas  of  Cortex,  in  addition  to  the 
existence  of  the  extra  layer  of  small  pyramidal  and  angular  nerve- 
elements  above  referred  to,  another  distinctive  character  is  to  be 
found  in  the  fact  that  the  large  cells  have  in  all  parts  of  the  con- 
volutions that  laminar  or  solitary  arrangement  which  in  the  so-called 
'  motor  area  '  exists  only  at  the  bottom  of  the  '  sulci '  *  :  (5)  that 
transition  regions,  or  convolutions,  exist  where  the  six-laminated 
arrangement  seems  to  be  giving  place  to  the  five-laminated 
arrangement,  and  that  almost  precisely  similar  transitions  are  to 
be  seen  even  in  the  five-laminated  regions  on  passing  from  the 
bottom  of  the  '  sulci '  to  the  sides  of  the  Convolutions. 

Although  they  differ  so  mucli  in  size  the  proper  nerve 
elements  of  the  second,  third,  and  fourth  layers  are 
essentially  similar  in  shape,  and  there  is  really  no  good 
ground  for  separating  these  strata  from  one  another.  It 
may  be  warrantable  as  a  mere  artifice  for  facilitating 
description,   but  is   not  warrantable  if  the   fact   of  such 

*  The  fact  that  these  two  layers   {i.e.,  the  '  fourth '   and  the 

*  fifth  '  of  the  six-laminated  areas)  are,  as  Bevan  Lewis  points  out, 
always  developed  in  inverse  proportion ;  and  the  fact  that  whero 
the  former  is  nominally  absent  {i.e.,  in  the  five-laminated  areas) 
"small  angular  cells"  still  exist,  intermixed  with  the  so  called 
'  giant  cells ',  make  it  possible  that  we  have  here  the  above  two 
layers  merged  into  one,  owing  to  the  extreme  development  of  some 
of  the  nerve  elements  otherwise  existing  as  small  pyramidal  cells. 


450 


THE    INTERNAL    STRUCTURE 


division  is  to  be  taken  as  implying  that  there  is  any 
difference  in  kind  between  these  pyramidal  elements, 
although  they  differ  so  much  in  size  in  different  situations. 
To  speak  of  the  largest  of  these  cells  only,  viz.,  those  of 
the  fourth  layer  as  '  ganglionic '  cells,  and  of  this  layer  in 
particular  as  '  the  ganglionic  layer,' 
carries  with  it  misleading  implica- 
tions. Even  the  largest  of  the 
clustered  cells  differs  only  in  degree 
from  similarly- shaped  cells  found  in 
the  layer  above,  and  also  in  the  same 
layer  throughout  those  other  portions 
of  the  cortex  which  do  not  possess 
these  cells  in  '  nests  '  or  clusters. 

The  most  consistent  conclusion  to 
be  drawn  from  these  facts,  by  those 
who  adopt  Ferrier's  views,  would  be 
for  them  to  say  that  all  convolutions 
-Section  of  the  coutaiu  '  motor  cells  '  —and  that  too 
in  more  than  one  layer — unless  the 

'  grouping  ' 


Fio.  lei 

Involuted  Layer  of  the  Hip- 
pocai  ipus    (or    Cornu     Am- 

mopis).     A,   White  fibres,   niero  fact  of  the  nest-like 

wjiicli  here,  owing  to  absence  in  •  •  • 

of  spindle  and  small  cell  of  the  cclls  lu  Certain  situatious  IS  to 

'ayers,  attach  themselves  im 
mediately  to  C,  the  pyrt- 
midal  cells  equivalent  to  tiie 
iniier  half  of  the  third  layer 
of  the  five-laniinated  cortex  ; 
r,  'stratum  radiatum,'  corre- 
sponding to  outer  hdf  uf 
third  layer  ;  m,  I,  equiva- 
lents of  the  first  and  second 
layers. 


be  taken  as  an  indication  that  such 
cells  have  assumed  '  motor  functions,' 
and  are  on  that  account  to  be  desig- 
nated as  '  ganglionic'  Either  of 
these  positions  would,  however,  pro- 
bably seem  to  the  ordinary  reader  to 
be  very  poorly  based  on  anything 
like  reasonable  considerations. 

It  is  worthy  of  note  that  in  the  involuted  grey  layer  of 
the  '  Hippocampus  major,'   the  structure  of  the    cortical 
matter,  as   Meynert  points  out,*  is  extremely  simplified, 
*  Strieker's  "  Human  cand  Comp.  Histology,"  vol.  ii.  p.  395. 


CiiAF.  XXIII.]  OF    THE    HUMAN    BRAIN.  451 

since  the  nerve  elements  of  this  region  are  represented  by 
a  single  stratum  of  pyramidal  cells,  which  differ  also  only 
in  size  from  the  so-called  '  giant  cells  '  of  the  parietal  or 
frontal  Convolutions. 

There  is  in  fact,  in  the  writer's  opinion,  no  valid  reason 
for  supposing,  as  many  do,  that  these  '  giant-cells '  differ 
at  all  in  kind  from  others  of  smaller  and  smaller  size  with 
which  they  are  intermixed,  or  which,  in  the  corresponding 
layer,  alone  exist  in  so  very  many  of  the  convolutions  of 
the  Cerebrum. 

Similar  kinds  of  cell  elements  to  those  found  in  the  Convolutions 
of  the  Human  Brain,  and  similarly  arranged,  are  to  be  found  in 
the  Convolutions  of  Apes  and  Monkeys. 

In  lower  animals  the  greatest  portion  of  the  Cortex  is  also  six- 
laminated,  but  in  certain  special  and  limited  (thoigh  varying) 
regions  in  each  kind,  a  five-laminated  Cortex  exists.  These  laminoB, 
according  to  Bevan  Lewis,  are  also,  to  a  considerable  extent,  iden- 
tical in  composition,  though  the  first  (which  is,  in  the  main,  a  mere 
connective  tissue  layer)  has  generally  a  greater  comparative  depth 
in  the  Sheep,  the  Pig,  and  other  lower  animals,  than  in  Man.  He 
says: — "  It  is  in  the  essential  character  of  the  individual  cells  of 
these  layers,  in  the  relationship  of  these  anatomical  units  the  one 
to  the  other,  and  in  their  general  distribution,  that  we  detect  diver- 
gence from  the  type  normal  to  the  higher  Mammalia." 

In  Man,  the  Ape,  the  Cat,  and  the  Ocelot,  the  '  giant '  cells  are 
swollen  and  more  rounded  (owing  to  their  giving  ofi'  a  larger  num- 
ber of  processes),  than  in  such  animals  as  the  Sheep  and  the  Pig. 
In  the  latter  these  cells  are  more  simply  pyramidal,  and  have  a 
smaller  number  of  inter-connecting  processes.  Such  cells  are, 
moreover,  scattered  over  a  wide  area.  But  in  the  Cat  and  otl^er 
Carnivora,  the  area  in  which  the  *  giant '  cells  are  found  is  very 
restricted — much  more  so  than  in  Man  and  the  Quadrumana,. 

Again,  according  to  Bevan  Lewis,  a  peculiar  kind  of  '  globose  * 
cell  with  few  connecting  processes,  is  to  be  found  amidst  the  other 
elements  in  the  second  and  third  layers  of  the  Pig  and  Sheep,  and 
also  in  Apes — though  such  elements  have  been  met  with  in  Man 
only  in  the  brains  of  Idiots  or  Imbeciles. 


452 


THE    INTERNAL    STRUCTURE 


4.— The  Principal  Commissures  of  the  Brain. 

The  connecting  or,  as  Meynert  terms  them,  the  '  associa- 
tion system  '  of  fibres  of  the  Brain  belong  to  three  principal 
categories,  each  of  which  will  be  now  briefly  described. 


Fig.  1G2.— Longitudinal  Section  through  the  centre  of  the  Brain,  showing  the 
inner  face  of  Left  Cerebral  Hemisphere.  (Sappey,  after  Hirschfeld.)  1,  Spinal 
Cord  ;  2,  Pons  Varolii ;  3,  Cerebral  Peduncle  ;  4,  '  Arbor  Vita? '  of  cut  surface  of 
Middle  Lobe  of  CereV>ellum  ;  5,  Sylvian  aqueduct ;  6,  Valve  of  Vienssens  ;  7,  Corpora 
quadrigemina ;  8,  Pineal  body  ;  9,  its  inferior  peduncle  ;  10,  its  eupeiior  peduncle ; 
11,  middle  portion  of  the  great  Cerebral  Cleft;  12,  upper  face  of  the  Tlialamus  ; 
13,  its  internal  face,  forming  one  of  the  walls  of  the  middle  or  Ihird  ventricle; 
13',  Grey  or  Middle  Commissure;  14,  Choroid  plexus;  15.  Pituitary  pedicle; 
16,  Pituitary  body  ;  17,  Tuber  cincreum  ;  18,  Mammillary  body  ;  19,  interpeduncxdar 
perforated  lamella;  20,  third  or  common  Oculo-motor  nerve;  21,  Optic  Nerve; 
22,  Anterior  Commissure ;  23,  Foramen  of  Monro ;  24,  section  of  the  Cerebral 
trigone  ;  25,  Septum  lucidum  ;  26,  Corpus  Callosum  ;  27,  its  posterior  extremity  or 
'  bourrelet  ;  28,  its  anterior  extremity  or  'genu  ' ;  29,  30,  Gyrus  fornic.itus,  or  Con- 
volution of  the  Corpus  Callosiun ;  31.  Anterior  part  of  Marginal  Convolution; 
32,  Calloso-marginal  sulcus;  33,  Occipital  Co7ivolutions ;  34,  '  internal  perpendicular 
fissure  '  separatiug  Occipital  from  Parietal  Lobe. 

These  fibres  are  of  great  importance,  and  so  numerous, 

that,  Broadbent  says,*  "  the  radiating  fibres  must  bear  a 

*  "  Journ.  of  Merit.  Science,"  Ap.  1870,  p.  9. 


Chap.  XXIII.]  OF    THE    HUMAN    BRAIN.  453 

small  proportion  to  the  fibres  passing  from  one  part  of 
the  surface  to  another." 

a.  Commissures  connecting  similar  parts  in  the  two 
Hemispheres. — These  are  generally  spoken  of  under  the 
name  of  '  transverse '  Commissures.  They  include  the 
Corpus  Callosum,  the  Anterior  Commissure,  together  with 
the  Middle  and  Posterior  Commissures.  A  part  of  them 
have  been  hitherto  referred  to,  in  the  quotations  from 
Broadbent's  descriptions,  as  *  callosal '  fibres. 

The  Corpus  Callosum  is  by  far  the  largest  and  most 
important  of  all  the  commissures.  When  the  two  Cere- 
bral Hemispheres  are  separated  it  may  be  seen  as  a  broad 
band  of  fibres  extending  from  the  one  to  the  other.  Its 
antero-posterior  diameter  is  over  three  inches,  whilst 
laterally  it  extends  into  the  substance  of  each  Hemisphere, 
where  it  forms  the  roof  of  the  '  lateral  ventricles.'  On 
section  it  is  seen  to  be  thickened  at  each  extremity 
(fig.  162,  27,  28). 

Various  notions  have  been  held  by  older  anatomists  as 
to  the  distribution  of  the  fibres  of  the  Corpus  Callosum 
which  need  not  now  be  discussed,  though  it  may  be 
mentioned  that  Foville  thought  its  fibres  served  to  bring 
the  Crus  of  one  Hemisphere  into  relation  with  that 
of  the  other  ;  and  that,  according  to  Gratiolet,  its  fibres 
suffice  to  bring  the  Crus  of  one  side  into  connection  with 
the  convolutions  of  the  opposite  Hemisphere.  The  inves- 
tigations of  both  Meynert  and  Broadbent,  however,  lead 
them  to  believe  that  the  first  of  these  \iews  is  altogether 
erroneous  and  that  the  second,  if  at  all,  is  onl}  very 
partially  true,  since  in  the  main  the  fibres  of  the  Corpus 
Callosum  serve  to  unite  similar  Convolutions  in  the  two 
Hemispheres.*  Its  fibres  are  not,  however,  distributed  to 
all  alike,  but  only  to  some  of  them.  And,  as  before 
*  "  JoLirn.  of  Meiit.  Science,"  Ap.,  1870,  p.  18. 


454 


THE    JNTERNAL    STRUCTURE 


stated,  the  Convolutions  that  are  thus  brought  into 
relation  in  the  two  hemispheres  are  precisely  those  with 
which   the  '  radiating  fibres '    of   the    Crus    are    also    in 

relation.  The 
names  of  these 
Convolutions 
have  been  al- 
ready given  (p. 
444). 

The  Anterior 
Commissure  is 
a  distinct  band 
of  w^hite  fibres 
which  crosses 
the  anterior 
part  of  the 
*  third  ventricle' 
and  on  each 
side  penetrates 
the  substaiice 
of  the  Corpus 
Striatum  (fig. 
164,  6).  It  is 
not,  however, 
as  it  seems  to 
be,  a  Commis- 
sure connecting 
these  bodies. 
Careful  dissec- 
tion suffices  to 
show  that  its  fibres  merely  pass  through  the  Corpus 
Striatum  on  each  side  (where  they  lie  in  a  distinct  groove 
or  canal),  that  they  emerge  on  the  under  and  outer  surface 
of  these    bodies,    and    that  they  are   thence  distributed 


Fin.  163. —Horizontal  Section  throiigli  the  Cranium  and 
Cerebral  Hemisphere  just  above  the  level  of  the  Corpus 
Callosum,  showing  the  so  called  'centrum  ovale '  of  Vieus 
sens.  (Sappey,  after  Vicq  d'Azyr.)  1,  1,  Median  furrow  of 
the  upi^er  face  of  the  Corpus  Callosum  ;  2,  2,  longitudinal 
fasiculi  of  this  face  ('nerves  of  Lancisi');  3,  the  transverse 
fasiculi  of  its  main  body ;  3',  section  of  the  medullary  sub- 
stance at  the  level  of  the  border  of  the  Corpus  Callosum  ; 
4,  4,  grey  layer  of  the  Convolutions  forming  an  irregular 
festoon  around  the  '  centrum  ovale  '  of  Vicus.scns  ;  5,  ante- 
rior part  of  the  great  longitudinal  fissure  of  the  Cerebrum  ; 
6,  posterior  part  of  this  longitudinal  fissure ;  7,  7,  section  of 
the  walls  of  the  Skull. 


Chap.  XXIII.] 


OF    THE    HUMAN    BRAIN. 


455 


to  the  convolutions  forming  the  tip  and  inner  or  under  sur- 
face of  the  Temporal  Lobe.  It  is,  as  Broadbent  says,  and 
as  other  anato- 
mists had  pre- 
viously recog- 
nized, a  sort  of 
accessory  Cor- 
pus Callosum 
connecting 
those  parts  of 
the  two  Tem- 
poral Lobes 
which  could  not 
otherwise  be 
easily  brought 
into  relation 
with  one  an- 
other. 

In  some  of 
the  lower  ani- 
mals that  have 
large  Olfactory 
Lobes  and 
'  tracts,'  these 
are  directly  con- 
nected with  one 
another  by 
means  of  fibres 
which  form  part 
of  this  Anterior 
Commissure. 

The  Middle  Commissure    is    a    soft 
matter  that  passes   across  the  '  third  ventricle 
Thalamus  to  the  other   (figs.  164,9;    157,  Th) 


Fig.  164. — Horizontal  Section  through  the  Cerpbrum  at  a 
deeijer  level,  showing  the  Third  Ventricle  and  its  Commis- 
sures and  the  relations  of  each  Corpus  Striatum  to  the 
Island  of  Reil.  (Sappey. )  1,  Fornix,  together  with  Velum 
Interpositum  turned  backwards  in  order  tx)  reveal  the  Third 
Ventricle  :  2,  Veins  of  Galen ;  3,  anterior  extremity  of  the 
Pineal  body  ;  4,  its  superior  peduncles ;  5  Posterior  Cere- 
bral Commissure;  6,  Anterior  Commissure;  7,  section  of 
anterior  pillars  of  Fornix  ;  8,  Third  or  Middle  Ventricle ; 
9,  Grey  or  Middle  Commissure  ;  10,  Corpus  Striatum,  the 
upper  and  external  strata  of  which  have  been  sliced  off; 
11,  Thalamus  ;  12,  Taenia  Semicircularis  ;  i3,  14,  15,  section  of 
Convolutions  of  the  Island  of  Reil ;  16,  section  of  the  intra- 
ventricular nucleus  of  the  Cori^us  Striatum;  17,  section  of 
the  White  Substance  of  the  Hemisphere,  at  the  part  which 
intervenes  between  the  Island  of  Reil  and  the  upper  part  of 
the  Cori)us  Stri  .turn. 


bridge  of  grey 
from  one 
and  may 


456  THE  INTERNAL  STRUCTURE 

therefore  serve  to  bring  parts  of  these  bodies  into  func« 
tional  relation  with  one  another. 

The  Posterior  Commissure  is  a  small  white  band 
which  passes  across  the  upper  and  posterior  boundary  of 
the  '  third  ventricle  '  (fig.  164,  5),  and  bends  downwards 
through  the  Thalamus  on  each  side  so  as  to  terminate 
in  the  ganglionic  matter  of  the  Tegmentum. 

The  existence  of  these  commissural  connections  between 
the  Thalami  are  specially  worthy  of  note,  when  we  find 
the  two  Corpora  Striata  quite  unconnected  by  Commissures 
of  any  kind.  It  is,  how^ever,  important  that  the  various 
centres  in  relation  with  *  ingoing '  impressions  should 
be  in  functional  connection  with  one  another,  while  no 
similar  necessity  exists  for  such  Commissures  between 
the  great  superior  motor  ganglia — since  each  Corpus 
Striatum  transmits  and  regulates  those  motor  incitations 
only  which  emanate  from  its  own  Cerebral  Hemisphere. 

b.  Commissures  connecting  clissimilar  parts  in  the 
same  Heniisj^h ere. —  Of  these  that  which  is  by  far  the  best 
knowai  is  the  Fornix.  This  is  generally  spoken  of  as  a 
longitudinal  commissure,  but  the  term  is  misleading, 
though  its  fibres  do  for  the  most  part  take  a  longitudinal 
direction.  They  serve  to  bring  the  inner  aspect  of  the 
Thalamus  and  the  Hippocampus  Major  of  the  same  hemi- 
sphere into  relation  with  one  another — these  being  parts 
which  are  almost  in  the  same  vertical  transverse  plane. 
The  course  and  functional  uses  of  its  fibres  have  been 
already  indicated  (p.  272). 

Two  accessory  sets  of  fibres  come  into  relation  with  the  '  anterior 
pillars'  of  the  Fornix; — (1)  a  narrow  band  of  fibres  on  each  side 
known  as  the  tcenia  semicircular  is,  which,  after  separating  from  the 
'  anterior  pillar  '  of  the  same  side  passes  backwards  in  the  groove 
between  the  Corpus  Striatum  and  the  Thalamus  and  disappears 
within  the  substance  of  the  latter  after  tnrnin"-  round  to  the  roof 


Chap.  XXIII,]  01'    THE    HUMAN    BRAIN.  457 

of  tlie  descending  cornu  *;  and  (2)  the  '  peduncles  '  of  the  Pineal 
Body,  which  pass  forwards  along  the  Thalamus  at  the  upper  limits 
of  the  '  third  ventricle,'  gradually  diminishing  in  size  and  at  last 
apparently  blending  with  the  '  anterior  pillars  '  of  the  Fornix  near 
the  anterior  extremity  of  each  Thalamus. f 

Many  other  sets  of  *  commissural  fibres  '  exist  on  each 
side  whose  office  also  is  to  bring  different  more  or  less 
distant  Convolutions  in  the  same  Hemisphere  into  relation 
with  one  another.  Some  of  the  principal  of  these  Com- 
missures are  longitudinal  in  direction,  and  are  disposed  in 
the  following  manner  : — J 

1.  A  great  'axial  longitudinal  system'  runs  through  the  upper 
portions  of  the  Hemispheres.  It  contains  fibres  from  the  Occipital 
and  Temporal  Lobes  which  pass  on  to  the  tip  of  the  Frontal  lobe, 
receiving  or  giving  fibres  along  this  route  to  many  overlying  con- 
volutions. 

2.  The  *  longitudinal  system  of  the  fasiculus  uncinatus '  is  a 
set  of  fibres  situated  at  a  lower  level  than  the  former,  though  it 
connects  the  same  main  divisions  of  the  Hemisphere.  Its  middle 
portion,  forming  the  band  from  which  it  takes  its  name,  is  to  be 
seen  on  the  lateral  aspect  of  the  hemisi3here,  crossing  the  bottom 
of  the  Sylvian  fissure  from  the  Frontal  to  the  Temporal  Lobe. 
Anteriorly  its  fibres  pass  beneath  the  Corpus  Striatum,  whence 
some  proceed  to  the  third  frontal  convolution,  others  spread  out 
beneath  the  orbital  convolutions  to  reach  the  anterior  extremity  of 
the  Corpus  Callosum  and  the  convolutions  at  the  adjacent  margin 
of  the  orbital  region,  though  the  great  majority  of  the  fibres  pass 
on  beneath  the  orbital  convolutions  to  end  along  the  anterior  edge 
of  the  Hemisphere.  Posteriorly,  the  fibres  of  the  fasiculus  unci- 
natus pass  to  the  tip  of  the  Occipital  Lobe  and  to  the  convolutions 
along  the  lower  and  outer  edge  of  the  Hemispheres,  whilst  a  con- 

*  This,  therefore,  would  seem  to  contain  fibres  serving  to  connect 
two  distant  portions  of  the  same  '  Thalamus  '  with  one  another. 

t  As  these  '  peduncles  '  of  the  Pineal  Body  are  continuous  with 
one  another  posteriorly,  they  may  form  a  sort  of  'transverse  com- 
missure' for  those  regions  of  each  Thalamus  from  which  the 
*  anterior  pillars  '  of  the  Fornix  proceed. 

X  See  "  Journ.  of  Mental  Science,"  Ap.  1870,  pp.  10-16. 


458  THE    INTERNAL    STRUCTURE 

siderable  group  of  them  also  proceeds  to  the  tip  of  the  Temporal 
Lobe. 

3.  Other  inferior  and  more  supci'ficial  loiigltudiiiOjl  fibres  pass 
from  the  tip  of  the  Temporal  Lobe  backwards  (diverging  as  they 
go)  into  the  floor  of  the  '  descending  cornu '  and  into  that  of  the 
posterior  cornu,  where  they  become  mixed  with  fibres  of  the  Corpus 
Callosum. 

4.  The  Convolutions  on  the  fiat  internal  surface  of  the  hemi- 
sphere, especially  the  '  gyrus  fornicatus,'  contain  longitudinal  fibres. 
These  latter  are  said  to  extend  from  the  *  anterior  perforated  space* 
in  front  (Corpus  Striatum)  backwards  over  the  Corpus  Callosum^ 
round  its  posterior  extremity,  and  thence,  according  to  Foville, 
onwards  to  the  tip  of  the  Temporal  Lobe. 

6.  Certain  longitudinal  fibres  {' nerves  of  Lancisi')  Sire  s,itu.a,ied 
on  the  upper  surface  of  the  Corpus  Callosum  in  two  series  on  each 
side  (fig.  1(53).  In  front  they  also  are  said  to  come  into  relation 
with  the  'anterior  perforated  space,'  whilst  posteriorly  their  des- 
tination is  doubtful.  According  to  Foville  they  join  the  '  posterior 
pillars  '  of  the  Fornix.* 

Other  sets  of  '  commissural  fibres '  are  not  so  distinctly 
longitudinal  in  direction,  and  they  serve,  moreover,  to 
bring  more  immediately  adjacent  Convolutions  into  rela- 
tion witli  one  another. 

We  still  possess  a  very  inadequate  knowledge  of  these 
multitudinous  sets  of  fibres,  but  it  would  be  quite  impos- 
sible here  to  attempt  to  render  an  account  of  all  that  has 
been  made  out  in  regard  to  them.  A  few  illustrations  of 
the  best  marked  of  these  connections  may,  however,  be 
given  in  order  to  convey  some  idea  of  the  extent  of  inter- 
relation existing  between  contiguous  Convolutions. 

Broadbent   saysf: — "The  second   or   groat   ascending  parietal 

*  These  last  two  sets  of  fibres  may  therefore  possibly  pass  by 
circuitous  routes  from  *  sensory '  regions  in  the  Temporal  Lobe  to 
the  corresponding  Corpus  Striatum.  Other  regions  of  this  Lobe 
seem  to  be  connected  with  the  same  body  in  a  much  more  direct 
manner,  i.e.,  by  fibres  which  cross  the  Sylvian  fissure  (p.  445). 

f  Loc.  cit.  p.  11. 


Chaf.  XXIII.]  OF    THE    HUMAN    BRAIN.  459 

gfyrus  has  complicated  connections  with  the  adjacent  convolutions 
behind  it,  and  receives  large  bands  of  fibres  from  the  posterior 
part  of  the  hemisphere  by  means  of  the  axial  longitudinal  system  ; 
it  is  also  extensively  connected  with  the  anterior  parietal  convolu- 
tion, and  sends  forwards,  deeply,  fibres  to  all  the  three  frontal  con- 
volutions. The  second  frontal,  besides  receiving  fibres  from  the 
axial  system  and  parietal  convolutions,  is  connected  with  the  first 
and  third  frontal  gyri,  between  which  it  lies,  by  numerous  large 
laminae,  which  do  not  simply  dip  transversely  under  the  interven- 
ing sulci,  but  run  tortuously  forwards  or  backwards,  tlieir  inter- 
twinings  being  too  complicated  to  admit  of  either  description  or 
representation.  Fibres,  moreover,  cross  transversely  under  the 
second  frontal  gyrus  from  the  first  to  the  third." 

The  convolutions  of  the  Temporal  Lobe  are  most  distinctly  con- 
nected with  others  in  the  Occij)ital  and  in  the  Parietal  TiObes,  and 
Broadbent  adds,*  it  is  "  worthy  of  mention  that  between  the  infra- 
marginal  Sylvian  and  parallel  gyri  separated  by  the  deepj  parallel 
sulcus,  there  is  the  most  extensive  commissural  connection  to  be 
found  between  adjacent  convolutions  in  the  entire  brain."  Recent 
physiological  experiments,  as  we  shall  see  in  the  next  chapter, 
render  this  observation  one  of  great  importance. 

The  bulk  of  the  fibres  from  the  radiating  convolutions  of  the 
*  island  of  Eeil,'  form  a  thick  layer  that  is  in  relation  with  the 
convolutions  into  which  its  anterior  and  upper  margins  pass,  viz.: 
those  of  the  posterior  border  of  the  orbital  lobule,  the  third  frontal 
and  the  ascending  parietal  gyri.  The  course  of  these  fibres  is  very 
intricate.  Fibres  also  pass  between  the  convolutions  of  the  '  island 
of  Eeil '  and  the  posterior  part  of  the  hemisphere ;  whilst  a  few 
proceed  from,  or  pass  between,  the  centre  of  the  island  from  the 
overhanging  tip  of  the  Temporal  Lobe.  No  fibres  connecting  these 
convolutions  with  the  Corpus  Striatum  or  Thalamus  have  yet  been 
recognized,  although  they  lie  immediately  outside  the  former  body, 
and  may  therefore  receive  a  few  filaments  from  its  extra-ventricular 
grey  nucleus. 

From  what  lias  been  said  concerning  the  distribution  of 
the  fibres  of  the  Corpus  Callosum,  of  the  various  longi- 
tudinal sets  of  '  commissural  fibres,'  and  of  those  which 
pass   in   different   directions  between  more  or  less   con- 

*  Loc.  cit.  p.  15. 


460  THE  INTERNAL  STRUCTURE 

tiguous  Convolutions,  the  reader  will  not  find  it  difficult 
to  believe  what  seems  for  many  reasons  probable,  that 
in  the  white  substance  of  the  Hemispheres,  the  mass  of 
which  is  so  large,  fibres  of  the  Crus  or  from  the  Central 
Ganglia  on  their  road  to  or  from  the  surface  must,  as 
Broadbent  points  out,  bear  a  small  proportion  to  the 
fibres  passing  from  one  part  of  the  surface  to  another 
either  in  the  same  or  in  opposite  Hemispheres — or,  to  put 
it  in  the  phraseology  of  Meynert,  the  fibres  of  the  '  pro- 
jection system  '  are,  in  the  aggregate,  small,  when  com- 
pared with  those  of  the  '  association  system.' 

c.  Commissures  bringing  the  Cerebellum  into  relation 
with  the  Cerebrum. — These  correspond  with  what  are 
known  as  the  Upper  Cerebellar  Peduncles,  though  it  is 
possible  that  the  Middle  Peduncles  ought  also  to  be  in- 
cluded under  this  category.  The  distribution  of  these 
parts  will  be  referred  to  in  the  next  section.  The  Lower 
Peduncles,  though  they  pass  through  a  portion  of  the 
Medulla,  serve  in  the  main  to  place  the  Cerebellum  in 
relation  with  the  Spinal  Cord. 


5.— The  General  Structure  of  the  Cerebellum^  and  its 
Relations  with  other  parts. 

The  Cerebellum  or  'Little  Brain,'  unlike  the  Cerebrum, 
is  a  solid  organ  whose  two  halves  are  continuous  with  one 
another.  If  a  horizontal  section  be  made  through  the 
middle  of  the  Cerebellum,  there  will  be  seen,  in  its  interior, 
on  each  side,  a  plicated  bag-like  nucleus  of  Grey  Matter, 
whose  open  extremity  is  directed  forwards  and  inwards 
(fig.  156,  14). 

The  different  Lobes  of  which  the  Cerebellum  is  composed 
have  been  already  referred  to,  as  well  as  the  manner  in 
which  they  are   subdivided.     But  the  extent  and  mode  of 


Chap.  XXIIL] 


OF    THE    HUMAN    BRAIN. 


461 


subdivision  of  the  surface  of  the  organ  will  be  best  com- 
prehended from  figs.  156,  162,  165.  These  show  the  rami- 
fied nature  of  the  peripheral  segments  of  the  Cerebellum 
and  the  large  proportional  bulk  of  its  surface  grey  matter, 
when  compared  with  the  mass  of  '  white  substance  '  which 
this  matter  everywhere  encloses,  except  in  the  direction  of 
its  Peduncles. 

The  Pedun- 
cles of  the  or- 
gan, of  which 
there  are  three 
pairs,  are  the 
parts  that  serve 
to  connect  it 
with  other  di- 
visions of  the 
Brain  and  with 
the  Spinal 
Cord. 

The  Upper 
Peduncles  of 
the  Cerebel- 
lum are  thick 
bands  of  fibres 


Fig.  165.— The  Upper  Peduncles  of  the  Cerebellum,  the 
Fourth  Ventricle,  and  contiguous  parts.  (Sappey,  after 
Hirschfeld.)  1,  Median  groove  in  floor  of  fourth  ventricle; 
2,  white  fibres  by  -which  the  auditory  nerve'  terminates ; 
.3,  inferior  Cerebellar  Peduncle;  4,  posterior  mod  an  column  ; 
that  proceed  5,  superior  Cerebellar  Peduncle,  crossing  the  inferior  on  its 
fiT»-iTi  ifcj  on  i'^'^^r  side;  6,  7,  ufjper  and  posterior  aspect  of  the  Cerebral 
II  Om      lis      an-     peduncle  ;  S,  Corpora  quadrigemlna. 

terior     border 

in  a  slightly  convergent  direction  to  the  posterior  pair  of 
the  '  quadrigeminal  bodies,'  beneath  which  they  pass.  In 
this  situation  they  decussate,  and  the  fibres  of  each  set 
then  proceed  to  a  large  nucleus  of  ganglionic  matter,  in 
the  upper  or  sensory  portion  of  the  Crus  Cerebri,  usually 
known  as  the  '  red  nucleus.'  Thence  the  course  of  these 
or  of  related  fibres  is  uncertain,  but  they  are  now  com- 


462  THE  INTERNAL  STRUCTURE 

monly  believed  to  pass  under  the  posterior  extremity  of 
the  Thalamus,  and  from  this  body  to  different  regions  of 
the  Cerebral  Cortex — though  they  have  not  been  actually 
traced  further  than  into  different  parts  of  the  '  corona 
radiata.' 

Nothing,  therefore,  is  known  as  to  the  particular  Con- 
volutions with  which  the  Cerebellum  is  brought  into 
relation  through  these  fibres  of  the  Upper  Cerebellar 
Peduncles.  On  the  Cerebellar  side,  however,  these  par- 
ticular fibres  are  thought  to  be  partly  in  immediate 
relation  with  the  cortex  of  the  inferior  portions  of  the 
Middle  Lobes  (fig.  165) ;  wdiilst  others  of  them,  on  each 
side,  are  in  communication  with,  or  enter  the  bag-like 
grey  nucleus  (fig.  156)  before  passing  to  different  portions 
of  the  Cerebellar  Cortex. 

Between  these  converging  Upper  Peduncles  there  is  a 
thin  lamina  of  nerve  matter  known  as  the  *  valve  of 
Vieussens '  that  suffices  to  connect  the  Middle  Lobe  of 
the  Cerebellum  with  the  Corpora  Quadrigemina.  This  is 
a  structure  which  in  lower  Vertebrates,  such  as  Fishes, 
is  proportionately  more  developed,  and  serves  to  bring  their 
large  '  optic  lobes '  into  structural  connection  with  the 
only  portion  of  the  Cerebellum  that  they  possess,  viz., 
the  Middle  Lobe.  This  lamina  forms  the  roof  of  the 
upper  or  anterior  half  of  the  '  fourth  ventricle '  (fig.  152) 
and  also  of  the  first  part  of  the  passage  between  this 
cavity  and  the  *  third  ventricle.* 

The  Lower  Peduncles,  or  '  restiform  bodies  '  as  they 
are  also  termed,  connect  the  Cerebellum  with  the  Medulla 
and  Spinal  Cord  (fig.  165).  Within  the  Cerebellum  the 
fibres  of  these  Peduncles  are  said  not  to  come  into  relation 
with  the  central  bag-like  grey  nuclei,  but  to  pass  at  once 
to  different  regions  of  the  cortical  grey  matter. 

The  inner  portion  of  each  Lower  Peduncle  appears  to 


CiiAP.  XXIIL 


OF    THE    HUMAN    BRAIN. 


463 


be  made  up  by  the  centripetal  prolongations  of  the  Audi- 
tory Nerve ;  the  fibres  of  which  are  traceable  from  its  own 
'  external  nucleus  '  to  the  '  nucleus  du  toit '  of  Stilling  on 
the  same  and  on  the  opposite  side.  But  the  outer  portion 
of  the  Pedun- 
cle, Meynert 
says,  is  de- 
rived from  the 
opposite  '  pos- 
terior column' 
of  the  Cord  in 
the  following 
manner.  The 
fibres  of  the 
posterior  me- 
dian column 
( '  funiculus 
cuneatus  et 
gracilis  ')  en- 
ter or  come 
into  relation 
with  the  gang- 
lion cells  of 
the  corres- 
ponding '  oli- 
vary body  ' ; 
thence  they 
cross  the  me- 
dian line  of 
the  Medulla, 
behind        the 

*  anterior  pyramids,'  to  pass  round  the  opposite  olivary 
body  before  emerging  in  the  form  of  '  arcuate  fibres  '  at 
the  posterior  and  lateral  region  of  the  Medulla.    Here  they 


Fig.  166.— The  Middle  Cerebellar  Peduncles  and  Pons, 
with  Contiguous  Parts.  (Sappey,  after  Hirschfeld.)  1, 
Optic  Commissure  ;  2,  Tube  r  Cinereum  and  Pituitary  ped- 
icle ;  3,  Corpora  mammillaria ;  4,  Inter-peduncular  space  ; 
5,  Cerebral  peduncle  ;  6,  6,  Median  groove  on  Pons,  with  (7) 
a  slight  prominence  on  each  side ;  8,  origin  of  the  trige- 
minus ;  9,  superior  transverse  fibres  of  the  Pons  ;  10,  10,  Its 
median  fibres  ;  11,  its  lower  fibres  dipping  beneath  the  foi- 
mc.r;  12,  12,  middle  Cerebellar  peduncles,  formed  by  the 
)inion  of  these  three  sets  of  fibres  ;  the  left  ptduncle  is 
divided  near  its  origin,  the  right  is  in  part  dissected  out. 
13,  Spinal  Cord;  14,  median  furrow  of  the  Medulla;  15,  15, 
decussation  of  the  pyramids  (16) ;  17,  Olivary  body ;  18,  Arci- 
form  fibres. 


464  THE    INTERNAL    STRUCTURE 

throw  themselves  into,  and  ascend  as  part  of,  the  Lower 
Peduncle.  Thus,  the  fibres  of  each  '  posterior  column  ' 
sink  beneath  the  surface  of  the  Spinal  Cord,  and  after 
passing  through  the  corresponding  '  olivary  body  '  and 
thence  crossing  the  middle  line  of  the  Medulla  and  pass- 
ing round  the  opposite  *  olivary  body,'  they  emerge  as 
parts  of  the  *  restiform  body  '  or  Lower  Peduncle  of  the 
Cerebellum.  This  arrangement  is  not  to  be  regarded  as 
established  beyond  the  reach  of  doubt :  it  is  in  fact  denied 
by  Luys. 

The  Middle  Peduncles  together  form  the  'pons  Varolii.* 
The  fibres  of  each  (fig.  166)  emerge  from  different  parts  of 
the  cortical  substance  of  the  corresponding  '  lateral  lobe  '  of 
the  Cerebellum  ;  and  whilst  a  few  of  its  fibres  are  believed 
to  be  '  commissural '  in  nature,  and  merely  to  pass  across 
from  one  to  the  other  of  these  lateral  lobes,  the  majority 
of  the  fibres  of  one  side  decussate,  at  the  middle  line, 
with  those  of  the  opposite  Middle  Peduncle.  By  their 
intervention  each  half  of  the  Cerebelhim  is  brought  into 
relation  either  with  the  motor  fibres  descending  from  the 
opposite  Corpus  Striatum  (in  the  corresponding  Cerebral 
Peduncle)  ;  or  else  with  some  of  the  cells  of  the  Corpus 
Striatum  itself,  owing  to  some  of  the  Cerebellar  pedun- 
cular fibres  bending  upwards  from  the  '  pons '  to  end  in 
these  ganglia — ^just  as  others,  taking  a  similar  course,  are 
thought  to  pass  through  them  on  their  way  to  the  Cere- 
bral Convolutions. 

All  that  is  positively  known  is,  that  each  '  lateral  lobe  ' 
of  the  Cerebellum  is  principally  in  relation,  through  its 
Middle  Peduncle,  with  the  '  motor  tract '  from  the 
opposite  Cerebral  Hemisphere.  And  this  fact  itself  is  one 
of  some  importance,  since,  amidst  all  the  other  doubts 
concerning  the  Cerebellum  it  would  seem  positively  to 
imply   that  the   bulk   of  the  fibres   of    these   particular 


CwAP.  XXm.]  OF    THE    HUMAN    BRAIN.  4G5 

Peduncles  are  '  outgoing  '  or  motor  fibres — a  conclusion, 
which  is  harmonious  with  other  evidence.  Whether,  how- 
ever, there  are  points  of  junction  with  cerebral  motor 
fibres  of  the  opposite  side  in,  or  in  the  neighbourhood 
of,  the  '  pons  '  itself,  as  Luys  imagines ;  or  whether  such 
cerebellar  fibres  really  pass  upwards  to  the  cells  of  the 
Corpora  Striata — or  even  beyond  them,  to  some  portions 
of  the  Cortex  of  the  Cerebral  Hemispheres — are  details 
which  cannot  at  present  be  decided. 

6.— The  Minute  Structure  of  the  Grey  Matter  of  the 
Cerebellum. 

The  cortical  Grey  Matter  is  uniform  in  appearance 
all  over  the  innumerable  folds  of  the  surface  of  the  Cere- 
bellum. To  the  naked  eye  it  is  divisible  into  two  layers 
(fig.  167),  an  outer  clear  grey,  and  an  inner,  as  well  as 
narrower,  greyish  red  layer.  Within  the  grey  layer  of 
each  fold  is  a  stem  of  white  substance. 

In  the  deepest  part  of  the  outer  layer  there  is  a  single 
row  of  large  ganglion  cells  yJuTo  ^^  ¥0^0  ^^  ^^  ^^^^^^  ^^ 
diameter,  whose  large  branching  arms  ramify  throughout  the 
whole  of  this  stratum,  becoming  finer  as  they  approach 
the  surface  (fig.  167,  b,  b).  The  ultimate  ramifications  of 
these  nerve  processes,  together  with  a  kind  of  connective 
tissue  substance,  unite  to  form  a  most  delicate  matrix  of 
fibres,  amidst  which  are  interspersed  a  number  of  small 
corpuscles.  These  are  either  mere  nucleoid  bodies  or 
small  angular  cells,  and  like  the  similar  corpuscles  in  the 
grey  matter  of  the  Cerebrum  it  is  impossible  to  say  which 
should  be  regarded  as  belonging  to  the  connective  tissue, 
and  which  have  a  right  to  the  title  of  nerve  elements. 
Many  of  them,  as  W.  H.  0.  Sankey  has  ascertained,  are 
in  direct  continuity  with  the  ramifications  of  the  ganglion 
cells.     Running  along  the   inner  part  of  this  layer  across 


466 


THE    INTERNAL    STRUCTURE 


the   direction  of  the  large  branches  of  the  ganghon  cells 
are  a  number  of  fine  nerve  fibres. 


Pio.  1(57.— Grey  Matter  of  the  Cerebellum,  Section  of,  magnified  about  400 
diameters.  (Sharpey,  after  Sankcy.)  a,  pia  mater  of  Cerebellum;  b,  b,  outer  grey 
lit^'er ;  c,  prcat  ganglion  cells ;  d,  inner  greyish-red,  or  so-called  graimle  layer ;  e,  stem 
of  white  fibres. 


Chap.  XXIII.]  OF    THE    HUMAN    BRAIN.  467 

The  great  ganglion  cells  encroach  upon  the  outer  border 
of  the  next  stratum,  which  is  the  so-called  '  granule  layer.' 
Here  are  massed  together  a  multitude  of  corpuscles  from 
fcu) "0  ^^  ^sVo"  ^^  ^^  ^^^^^^  ^^  diameter,  very  similar  to 
those  more  sparingly  scattered  through  the  outer  layer. 
The  inner  process  of  each  large  ganglion  cell  is  said  to  be 
single  and  undivided,  but  as  it  is  very  fine  it  is  soon  lost 
to  view  in  the  dense  '  granule  layer '  into  which  it  passes. 
The  mode  of  connection  of  the  central  stem  of  white  fibres 
with  the  granule  layer  and  with  the  elements  lying  out- 
side it,  is  at  present  very  uncertain.  '  Granules,'  or  cor- 
puscles of  the  same  kind,  are  also,  though  more  sparingly, 
scattered  through  this  white  substance. 

It  seems  most  probable  that  some  of  the  fibres  in  each 
stem  of  white  substance  are  '  afferent,'  and  that  others 
conduct  'efferent'  impressions  or  impulses.  The  former 
fibres  may  divide  in  the  '  granule  layer,'  so  as  to  come 
into  relation  wdth  two,  three,  or  more  of  the  great  ganglion 
cells ;  and  the  outgoing  stimuli  may  pass  from  these 
groups  of  cells  through  their  ramifying  branches  in  the 
outer  layer,  and  thence  through  continuous  rootlets  of 
*  outgoing '  fibres  which,  coalescing  as  they  go,  pass 
through  the  '  granule  layer,'  and  away  through  the  stem 
of  white  substance. 

This  latter  is  a  hypothetical  arrangement,  but  one  which 
seems  to  the  writer  to  be  most  in  accordance  with  the 
actual  structure  of  the  grey  matter  of  the  Cerebellum. 

7.— The  Central  Connections  of  the  Olfactory  and 
Optic  Peduncles,  as  well  as  of  other  Cranial 
Nerves. 

The  Olfactory  Peduncles  or  'tracts,'  and  the  Optic 
Peduncles  or  '  tracts '  are  generally  regarded  as  some- 
thing different  from  ordinary  nerves.     They  are   looked 


4G8  THE    INTERNAL    STRUCTURE 

upon  as  special  out-growths  or  prolongations  from  the 
Brain.  A  distinction  of  this  kind  is  undoubtedly  legiti- 
mate in  regard  to  many  of  the  lower  animals.  It  is  so, 
for  instance,  in  Fishes  as  well  as  in  some  Reptiles  and 
Mammals,  in  which  the  Olfactory  Centres  are  extremely 
well  developed ;  and  also  in  Insects  and  Cephalopods  in 
which  the  eyes  and  Optic  Centres  are  very  large.  But  in 
Man,  in  whom  neither  the  sense  of  Smell  nor  the  sense  of 
Sight  is  so  inordinately  developed,  and  in  whom  the  cor- 
responding primary  Centres  are  relatively  small,  any  such 
distinction  is  less  obvious.  In  his  case,  indeed,  there  is 
no  good  reason  for  maintaining  it,  in  regard  to  the  Optic 
*  tracts,'  since  these  parts  differ  little  in  appearance  from 
ordinary  nerves.  There  is  more  reason,  however,  for  such 
a  distinction  in  reference  to  the  Olfactory  '  tracts,'  because 
even  in  Man  the  Olfactory  Ganglia  exist  as  outlying  por- 
tions of  the  Brain,  from  which  minute  Olfactory  Nerves 
descend  to  the  nasal  passages. 

The  course  and  central  connections  of  these  parts 
require  to  be  briefly  set  forth. 

The  Olfactory  *  tract '  is  connected  with  the  posterior 
region  of  the  orbital  surface  of  the  Hemisphej-e  by  three 
roots  ;  of  these  the  external  goes  outwards  to  the  inferior 
extremity  of  the  Temporal  Lobe  of  the  same  side,  as 
may  be  easily  recognized  in  those  Mammals  in  which  the 
Olfactory  Lobes  arc  large,  though  only  with  some  difficulty 
in  Man.  The  inner  root  enters  the  Hemisphere  near  its 
inner  border,  and  a  little  in  front  of  the  Optic  Com- 
missure. The  further  relations  of  the  fibres  of  the 
Olfactory  Tracts,  and  the  fact  that  they  come  into  relation 
on  each  side  with  Convolutions  of  the  corresponding  and 
not  with  those  of  the  opposite  Hemisphere  will  be  subso- 
tjuently  referred  to  (see  pp.  482,  488). 

The  Optic  '  tracts '   are  the  continuations  of  the  Optic 


Chap.  XXIIL]  OF    THE    HUMAN    BRAIN.  469 

Nerves  backwards,  behind  the  Optic  Commissure.  Each 
*  tract '  is  in  contact  with  and  turns  round  the  outer 
border  of  the  Cerebral  Peduncle,  becoming  flattened  as  it 
proceeds.  Here  each  of  them  comes  into  rehition  with 
two  small  ganglionic  nodules  (known  respectively  as  the 
internal  and  external  *  geniculate  bodies  ')  situated  at  the 
posterior  extremity  of  the  Thalamus  (figs.  168,  e,  i;  156,  8), 
contiguous  to  the  adjacent  anterior  segment  of  the  Quadri- 
geminal  Bodies,  with  which,  as  well  as  with  the  Thalamus 
itself,  many  of  its  fibres,  if  not  all,  come  into  relation 
before  being  continued  onwards  to  certain  regions  of  the 
cortex  of  the  corresponding  Cerebral  Hemisphere. 

Although  the  subject  is  by  no  means  free  from  doubt 
and  uncertainty,  the  weight  of  evidence  seems  now  most 
in  favour  of  the  view  that  the  *  decussation  '  at  the  Optic 
Commissure  is  as  complete  in  Man  as  it  is  known  to  be  in 
lower  Vertebrates.*  This  subject  will  be  again  referred 
to  in  a  subsequent  chapter  in  connection  with  the  question, 
as  to  what  parts  of  the  Cortex  of  the  Hemispheres  are 
most  intimately  concerned  w^ith  Visual  Impressions. 

Thus  it  would  appear  that  Olfactory  Channels  do  not 
decussate  at  all,  and  that  Optic  Channels  decussate  com- 
pletely. Yet  the  crossing  of  the  latter  channels  takes 
place  outside  the  substance  of  the  Brain,  so  that  in  this 
respect  the  arrangement  difi'ers  from  that  which  will  be 
found  to  obtain  for  the  next  two  sensory  '  Cranial  Nerves,* 
viz.  :  the  Fifth  and  the  Auditory. 

The  position  of  the  Fifth   Nerve    and   its    superficial 

connection  with  the  lateral  aspect  of  the  '  pons  Varolii ' 

may  be  seen  in  (fig.  168,  v).      Its  sensory  fibres   after 

passing  through  the  '  Gasserian  '   ganglion  are   gathered 

together  into  the   '  greater  root, '  the  fibres  of  which,  like 

those  of  the  '  posterior  roots  '  of  the  Spinal  Nerves,  soon 

See  Ferrier,  "  Functions  of  Brain,"  pp.  70  and  166. 
21 


470  THE  INTERNAL  STRUCTORK 

cross  over  to  the  opposite  side,  and  go  to  form  part  of  the 
sensory  tract  or  '  tegmentum  *  of  the  opposite  Cerebral 
Peduncle  (see  p.  478). 

The  Auditory  Nerve  enters  the  side  of  the  Medulla  just 
below  the  '  pons '  in  close  relation  with  the  root  of  the 
Facial  Nerve.  About  the  subsequent  very  complicated 
course  of  its  fibres  we  still  have  much  to  learn.  A  large 
section  of  them,  at  least,  seem  to  enter  the  Cerebellum, 
and  the  mode  by  which  the  opposite  Cerebral  Hemisphere 
is  brought  into  relation  with  its  fibres  and  nuclei  of  origin 
is  altogether  obscure.  Meynert  even  says  :* — "  We  may 
regard  it  as  certain  that  no  extensive  immediate  connection 
of  the  auditory  nerve  with  the  Cerebral  lobes  exists,  but 
that  such  a  connection,  the  existence  of  which  may  be 
assumed  as  a  necessary  physiological  truth,  can  only  come 
to  pass  indirectly  through  the  Cerebellum.^* 

How  far  this  view  of  Meynert' s  is  absolutely  correct 
cannot  at  present  be  determined.  We  do  know,  however, 
from  evidence  which  will  be  subsequently  referred  to  in 
regard  to  Hemi-ansesthesia  (p.  487),  that  a  decussation 
of  auditory  channels  takes  place,  and  that  these  channels 
ultimately  becoijje  incorporated  with  other  fibres  of  the 
Cerebral  Peduncles  comprised  within  the  posterior  third 
of  what  is  known  as  the  *  internal  capsule.' 

It  must,  moreover,  not  be  forgotten  that,  according  to 
Cyon  (p.  218),  what  is  named  by  him  as  the  Space-nerve 
(Raumnerv)  is  also  bound  up  with,  and  forms  part  of  the 
trunk  commonly  known  as  the  '  Auditory.'  The  internal 
course  of  the  portions  belonging  to  each  of  these  nerves 
will,  if  this  view  be  correct,  have  to  be  subsequently 
determined  and  differentiated.  It  may  be  that  it  is  the 
fibres  of  this  Space-nerve  more  especially  which  come 
into  immediate  relations  with  the  Cerebellum  (see  p.  500), 
*  Strieker's  Histology,  vol.  ii.  p.  500. 


Chap.  XXIII.] 


OF    THE    HUMAN    BRAIN. 


471 


The  other  two  sensory  nerves  of  the  MecluFa,  the 
Glosso-pharyngeal  and  the  Pneumogastric,  will  be  referred 
to  in   the  next   section.     The   situation   of  the   '  motor  ' 


ci  ca.  cZ 


Fig.  168. — Enlarged  View  of  part  of  the  Base  of  the  Brain  to  which  the  Cranial 
Nerves  are  attached.     (Ferrier,  after  Allen  Thomson.) 

On  the  right  side  the  Convolutions  of  the  Central  lobe  (C),  or  Island  of  Eeil,  have 
been  left,  on  the  left  the  incision  has  been  carried  between  the  Thalamus  (?'//)  and 
the  Hemisphere.  I',  Olfactory  Nerve  cut  short ;  II,  Optic  Nerve  in  front  of  Com- 
missure ;  IF,  Right  Optic  tract,  e.  The  external,  and  i,  the  internul  'corpuo  genicu- 
latum ' ;  h,  Pituitary  body  ;  t  c,  Tuber  cinereum  and  infundibulum  ;  a,  one  of  cor- 
pora mammillaria  ;  P,  Cerebral  peduncle.  Ill,  Third  nerve  (oculo-motor)  ;  IV,  Fourth 
nerve  (f  atheticus) ;  P  V,  Pons  ;  V,  the  greater  root  of  Fifth  nerve  (trigeminus).  +, 
The  lesser  or  motor  root  ;  on  the  right  side  this  is  placed  on  the  Gasserian  ganglion. 
1,  2,  3,  The  three  divisions  of  the  Fifth  nerve  ;  6,  Sixth  nerve  ;  Vila,  the  Facial ; 
VII6,  the  Auditory  ;  VIII,  the  Vagus  or  Pneumogastric;  Villa,  the  Glosso-pharyn- 
geal;  VIII/j,  the  Spinal-accessory;  IX,  the  Hyp()-glossal ;  fl,  the  'flocculus'  of  Cere- 
bellum; pa,  anterior  Pyramid;  o,  Olivary  body;  r,  Restiform  body;  d,  anterior 
median  fissure  of  the  Spinal  Cord,  above  which  is  the  'decussation'  of  the  Pyramids  ; 
c  a,  the  anterior,  and  c  I,  the  lateral  column  of  the  Spinal  Cord. 

nerves  will  be  seen  by  an  examination  of  fig.  168,  though 
no  further  reference  to  them  is  here  needed. 


472  THE  INTERNAL  STRUCTURE 


8.— The  Connection  of  the  Visceral  System  of  Nerves 
with  the  Brain. 

The  relation  of  the  Systemic  Nerves  to  the  Brain  is  not 
essential!}'  different  in  Man  from  what  obtains  in  the  great 
majority  of  higher  Vertebrates.  In  all  alike  the  Visceral 
System  of  Nerves  is  divisible  into  two  parts,  whose 
connections  with  the  Brain  are  partly  '  direct '  and  partly 

*  indirect.' 

1.  The  Cerebral  Systemic  Nerves.— The  lowest  seg- 
ment of  the  Brain — the  Medulla — is  placed  in  immediate 
relation  with  the  greater  number  of  the  viscera  of  the 
body  through  the  intervention  of  the  Glosso-pharyngeal 
and  the  Vagus,  as  '  ingoing  '  nerves.  They  connect  it 
with  the  whole  length  of  the  alimentary  canal  below  the 
buccal  cavity ;  with  the  respiratory  organs ;  with  the  heart 
and  some  of  the  great  vessels ;  with  the  liver,  the  spleen, 
the  kidneys,  and  possibly  also  wdth  the  internal  organs  of 
generation. 

From  the  same  region  of  the  brain  (the  Medulla)  certain 

*  outgoing  '  fibres  are  also  given  off  to  some  of  the  above- 
mentioned  internal  parts  or  viscera.  These  efferent  or 
motor  fibres  are  not  gathered  together  into  separate 
trunks ;  they  are  principally  wrapped  up  with,  and  con- 
stitute parts  of,  the  Glosso-pharyngeal  and  the  Spinal 
Accessory  Nerves.  The  viscera  which  do  not  receive 
'  outgoing '  fibres  from  this  source  are  supplied  with  them 
from  the  Spinal  Cord  and  the  nervous  apparatus  now  to 
be  mentioned. 

2.  The  '  Great  Sympathetic '  is  an  elaborate  and 
extensive  sys  cm  of  nerves,  and  consists  of  the  follow- 
ing parts  : — {'(.)  A  gangllonated  cord  lying  on  each  side 
of  the  vertebral  column,  each  of  which  is  connected  above 
with  the  5th,    Lhe  Gth,  the  7th,  the    8th,   and  the  9th 


C.UP.XXIII.J  OF    THE    HCMAN    BRAIN. 


473 


17  1  t8^  «.^ 

1,  1,  P.eu„„ga.«o;  2,  Anastomose;  of  .he-'pneu.o,a.,ri„  witb  the  H„c^,„.„, : 


474  THE    INTERNAL    STRUCTURE 

pairs  of  Cranial  Nerves,  and  also  with  the  anterior  hranches 
of  the  several  Spinal  Nerves  along  the  whole  length  of 
the  Cord.  The  latter  communications  are  mostly  brought 
about,  on  each  side,  by  pairs  of  filaments  (some  of  whose 
fibres  are  'afferent'  whilst  others  are  'efferent'),  passing 
between  the  several  anterior  spinal  nerves  and  the  corre- 
sponding ganglia  of  the  '  Sympathetic  ' — the  latter  being 
situated  a  little  in  front  of  the  spinal  nerves  (fig.  170). 
Other  Ganglia,  moreover,  are  found  at  the  junctions  of 
some  of  the  above-mentioned  Cranial  Nerves  with  the 
lateral  cords  of  the  '  Great  Sympathetic' 

(b.)  From  the  ganglionated  cord  on  each  side,  numerous 
internal  hranches  are  given  off  which  unite  with  one 
another,  with  those  of  the  opposite  side,  and  with  filaments 
of  the  Vagus  Nerves,  so  as  to  form  either  great  Plexuses 
or  Ganglia,  or  both  together,  whence  multitudes  of  nerves 
are  sent  to  or  received  from  the  various  Viscera.  On  the 
course  of  these  latter  nerves  smaller  ganglia  are  often 
found. 

The  principal  systemic  Plexuses  are  situated  about  the 
heart  and  roots  of  the  respiratory  organs  ;  in  the  neigh- 
bourhood of  the  stomach  ('  solar  plexus ') ;  and  also  in 
the  vicinity  of  the  bladder  and  internal  organs  of  genera- 
tion. 

The  nerves  in  connection   with  those  Plexuses  which 


8,  its  anastomoses  with  a  Lrancli  of  the  Spinal-accessory  ;  4,  Pharyngeal  branch  ; 
5, superior  Laryngeal  nerve;  6,  external  Laryngeal;  7,  Laryngeal  plexus;  S,  sui-)erior 
Cardiac  nerve  ;  9,  middle  Cardiac  ;  10, 10,  recurrent  Laryngeal  nerve  ;  11,  Pulmonary 
ganglion  ;  12,  its  anastomoses  with  the  great  Sympathetic  ;  13,  posterior  pulmonary 
plexus  ;  14,  Esophageal  plexus  ;  15,  anastomoses  of  the  right  with  the  left  Pneumo- 
gastric;  16,  branches  of  the  Cardiac  extremity  of  the  Stomach  ;  17,  branches  of  the 
smaller  curvature  ;  18,  branches  of  the  anterior  face  ;  19,  lleitatie  branches  ;  20,  Glosso- 
phar3'ngcal  nerve ;  21,  Spinal-accessory;  22,  its  internal  branch  anastomosing  with 
the  Pneumogastric ;  23,  its  external  branch  iiroceeding  to  the  Trapezius  and  anas- 
tomosing with  (24)  the  fourth  Cervical  nerve  ;  25,  sui^crior,  and  2(3,  middle  Cervical 
ganglion  ;  27,  inferior  Cervical  ganglion  united  with  the  first  Dorsal ;  28,  29,  32, 
Dorsal  ganglia ;  30,  great  Splanchnic  nerve ;  31,  origin  of  the  Phrenic  nerve. 

In  this  figure,  the  Heart  has  been  cut  away,  the  left  Liuig  drawn  forward  and  iti 
root,  partly  disaected,  and  the  Liver  has  been  partly  i-eflccted  from  the  Stomach. 


Chap.  XXIII.] 


OF    THE    HUMAN    BRAIN. 


475 


proceed  from  or  to  the  Viscera  are  mostly  distributed  along 
the  course  of  the  Blood-vessels.  Some  of  the  fibres 
of  this  system  are  specially  distributed  to  the  coats 
of  the  Vessels,  and  are,  from  the  nature  of  their 
functions,  known  as  'vaso- 
motor nerves.'  A  portion  of . 
these  must  have  '  afferent '  func- 
tions whilst  others  transmit 
'  efferent '  impulses,  causing  the 
vessels  to  contract,  so  that  by 
means  of  such  nerves,  the 
amount  of  blood  flowing  through 
particular  vascular  territories 
may  be  easily  regulated.  The 
'  vaso-motor '  nerves  are  con- 
nected with  small  ganglia  dis- 
tributed over  the  vessels.  To 
some  extent  motor  stimuli 
emanate  from  these,  though  the 
whole  '  Vaso-motor  '  system  of 
the  body  seems  to  be  amenable 
to  the  influence  of  a  'regulative 
centre '  situated  in  the  Medulla, 
together  with  other  subordinate 


Fig.  170.— One  of  the  Sympathetic 
Ganglia  from  the  right  Lateral  Cord 
of    the  Rabbit.      (Owen,  after    Kol- 
liker.)     Tr,  Literal  cord  of  Sympa- 
tem    probably    contains    its    own    thetlc ;    Rc,  Rc,  two  communicating 


centres  in  the  Spinal  Cord. 
Whilst  the  Sympathetic  Sys- 


intrinsic    afferent    and    efferent 


branches  ;    Spl,    Splanchnic  or  Vis- 


ceral nerve  ;  s,  small  nerve ;  g,  gan- 

nerves,  it  also  seems   to    send  ^'^^^^  ^®"^  ^"^  ^^^^^-   (^  about  40 

diameters.) 

(through  the   before -mentioned 

communicating  filaments)  afferent  nerves  to  the  grey 
matter  of  the  Spinal  Cord,  and  to  receive  therefrom  certain 
efferent  motor  and  other  fibres.  This  great  Sympathetic 
System  of  nerves  is  to  a  certain  extent   an  independently 


476       INTERNAL    STRUCTURE    OF    HUMAN    ERAIN. 

develo])ed  system,  though  it  also  holds  relations  to  the 
Spinal  Cord  closely  resembling  those  which  exist  between 
the  two  '  Cerebral  Systemic  Nerves,'  and  the  Medulla. 

By  the  arrangements  above  described,  not  only  is  the 
harmonious  activity  of  related  Viscera  facilitated,  but  the 
simultaneous  activity  of  Visceral  and  Cerebro-  spinal  Nerve 
Centres  is  ensured,  where  such  conjoint  activity  is  needed 
• — as  in  the  respiratory  processes,  in  oviposition  and  in 
parturition,  or  in  the  voiding  of  excreta.  Again,  by  reason 
of  the  direct  or  indirect  connection  of  the  Viscera  with 
the  Brain,  the  organic  states  of  the  various  organs  are 
capable  of  influencing  the  'temper'  or  mental  state  of  the 
individual,  either  unconsciously  or  consciously.  Visceral 
states  may,  independently  of  their  conscious  realization, 
prompt  to  automatic  or  Instinctive  Acts  ;  or,  they  may  im- 
press themselves  upon  the  Conscious  Life  of  the  individual, 
and  lead  more  or  less  directly  to  a  series  of  Voluntary 
Actions. 


CHAPTER  XXrV. 

THE  FUNCTIONAL  RELATIONS  OF  THE  PRINCIPAL  PARTS  OP 
THE  BRAIN. 

We  DOW  pass  from  the  consideration  of  details  of  struc- 
ture to  the  question  of  their  significance,  and  shall 
attempt  to  enable  the  reader  to  form  some  notions — 
meagre  though  they  may  be — of  the  way  in  which  the 
Brain  acts  in  the  performance  of  the  simpler  of  its 
functions. 

In  this  attempt  we  shall  have  to  be  guided  by  three 
sets  of  facts  and  inferences  : — (1)  Those  gathered  from  the 
study  of  the  Anatomy  of  the  Nervous  Systems  of  lower 
animals  and  of  Man ;  (2)  those  derived  from  Experiments 
with  lower  animals,  in  which  Nerves  or  other  portions  of 
the  Nervous  System  have  been  either  stimulated  or 
destroyed ;  (3)  those  reported  by  medical  men  who  have 
paid  special  attention  to  the  symptoms  arising  from  irri- 
tative or  destructive  Diseases  or  Injuries  of  different  por- 
tions of  the  Brain  in  Man. 

In  each  of  these  directions  our  knowledge  has,  within 
recent  years,  been  making  very  appreciable  strides  and 
is  still  progressing. 

In  this  preliminary  chapter  on  the  mode  of  action  of 
the  Brain,  the  reader's  atiention  will  be  called  to  what  is 
known  concerning  three  sets  of  structural  relations  which 
are  of  fundamental  importance. 


478  THE    FUNCTIONAL    RELATIONS    OF   THE 

1.— The  Cross  Eelation  existing  between  the  Cere- 
bral Hemispheres  and  the  Lateral  Halves  of  the 
Body. 

The  bodies  of  the  great  majority  of  Invertebrates,  as 
well  as  of  Vertebrate  Animals,  are  bilaterally  symme- 
trical— at  least  as  regards  all  external  organs  and 
all  parts  of  their  Nervous  System.  So  that  if  a  median 
vertical  plane  were  to  divide  one  of  these  animals  in  a 
longitudinal  direction,  each  half  of  the  body  would  be 
found  to  be  similar  to  the  other  in  all  respects  externally, 
and  each,  also,  would  contain  the  half  of  a  Nervous  System 
similar  to  that  of  its  fellow. 

So  far  as  we  know  at  present,  however,  the  relation 
which  the  double  Nervous  System  of  the  Invertebrate 
bears  to  its  double  body  is  different  altogether  from 
the  relation  subsisting  between  the  same  parts  in  the 
Vertebrate.  In  the  former  the  half  of  the  Brain  con- 
tained in  either  half  of  the  body  is  in  immediate  connec- 
tion with  the  sensory  organs  and  surfaces,  as  well  as 
with  the  motor  nerves  and  muscles,  of  the  same  side  of  the 
body.  In  Vertebrates,  on  the  other  hand,  it  is  not  so. 
In  lower  members  of  the  series  to  some  extent,  and  in 
the  higher  forms  (including  Quadrumana  and  Man) 
to  a  more  perfect  extent,  a  cross  relation  exists  between 
the  Brain  and  the  body,  so  that  each  half  of  the  Brain 
is  connected  with  the  Sensory  Organs  and  surfaces  of 
the  opposite  half  of  the  body,  and  also  with  its  Muscles. 
The  former  relation  is  brought  about  by  the  '  sensory ' 
channels  decussating  at  the  base  of  the  Brain  and  along 
the  Spinal  Cord  ;  and  the  latter  is  due  to  the  fact  that 
the  nerve-channels  for  '  outgoing  '  or  motor  stimuli  pass 
from  each  half  of  the  Brain  to  the  opposite  side  of 
the  body,  decussating  with  one  another  in  the  Medulla. 


Chap.  XXIV.]    PRINCIPAL  PARTS  OF  THE  BRAIN.  479 

Very  few  explanations  have  as  yet  been  attempted  of  the 
mode  of  origin  of  this  crossed  relation  between  the  Brain 
and  the  body.  The  subject  is  generally  passed  over  in 
silence,  and  though  our  knowledge  of  the  exact  anatomical 
relations  existing  in  lower  animals  is  not  yet  ripe  enough 
for  a  thoroughly  satisfactory  answer,  a  few  suggestions 
may  here  be  offered  which,  if  they  do  nothing  else,  will 
perhaps  serve  to  direct  more  attention  to  this  very  inte- 
resting question,  and  at  the  same  time  indicate  some 
of  the  directions  in  which  more  precise  information  is 
needed. 

The  essential  nature  of  the  problem  comes  out  most 
distinctly  if  the  reader  attempts  to  picture  to  himself  the 
existence  of  a  double  Nervous  System  in  Vertebrates  in  all 
respects  similar  to  what  it  is,  except  for  the  fact  that 
neither  its  sensory  nor  its  motor  channels  decussate. 
With  the  two  halves  of  the  Brain  and  Spinal  Cord,  as 
freely  connected  by  transverse  '  commissures '  as  they  are  at 
present,  a  direct  relationship  of  this  kind  would  seem  to 
be  the  most  natural  arrangement,  and  it  is  not,  therefore, 
at  all  clear  why  such  a  plan  should  not  exist  and  work  as 
well  for  Vertebrates  as  it  does  for  Invertebrates.  The 
question  to  be  answered,  then,  is — What  conditions  have 
arisen  in  Vertebrate  Animals  tending  to  initiate,  and 
finally  to  perfect,  such  a  crossed  relation  between  the 
Brain  and  the  body  as  we  find  existing  in  Man  and  the 
higher  Mammalia  generally  ? 

The  following  considerations  seem  to  the  writer  to 
throw  some  light  upon  this  subject  :— 

1.  Movements  take  place  in  response  to  sensory  impressions  of 
various  kinds,  and  (for  our  present  purpose)  they  may  be  divided 
into  two  classes : — {a)  those  in  which  related  muscles  on  the  two 
sides  of  the  body  are  called  into  simultaneous  activity — as  with  the 
trunk  muscles  concerned  in  the  locomotions  of  Fishes  and  many 


i80  THE    FUNCTIONAL    RELATIONS    OF    THE 

limbless  Keptiles  ;  and  (b)  those  in  which  muscles  on  one  side,  and 
especially  of  one  limb,  are  called  into  activity  alone — either  in  an 
ordinary  reflex  or  in  a  volitional  manner. 

2.  The  great  bulk  of  the  movements  of  Fishes  and  of  Ophidian 
Eeptiles  would  belong  to  the  former  category,  and  as  Broadbent* 
first  pointed  out  (in  regard  to  Man)  we  have  evidence  to  show  that 
movements  of  this  class  may  be  equally  well  evoked  by  a  stimulus 
passing  from  either  side  of  the  Brain  to  one  of  the  halves  of  their 
double  but  intimately  combined  Spinal  Centres.  This  being  so,  it 
would,  perhaps,  be  a  matter  of  comparatively  little  importance  for 
such  creatures  whether  some  particular  leading  sense  organs,  such 
as  the  eyes,  were  respectively  in  structural  connection  through 
their  optic  nerves,  with  the  half  of  the  brain  on  the  same  side 
or  with  that  of  the  opposite  side. 

3.  Fishes  are  the  animals  in  which  we  first  find  a  cross  arrange- 
ment of  certain  important  sensory  channels.  Their  Optic  ISTerves 
decussate  in  a  very  complete  manner.f  We  do  not  know  for  cer- 
tain, however,  that  any  of  their  other  sensory  channels  are  similarly 
disposed  ;  neither  is  there  any  evidence  to  prove  that  the  fibres  con-. 
Btituting  their  motor  channels  decussate  with  one  another. 

4.  In  Fishes,  then,  we  have  to  do  with  what  may  be,  and  prob- 
ably is,  a  mere  partial  initiation  of  the  cross  relation  between  the 
Brain  and  the  body  ;  and  it  seems  conceivable  that  such  a  relation 
may  have  been  determined  in  some  of  the  earliest  Fishes,  or  at 
least  favoured,  by  two  or  three  of  the  physical  peculiarities  of  such 
creatures.  The  elongation  of  the  head  of  a  Fish — a  conformation 
which  is  doubtless  in  intimate  relation  with  the  animal's  life  and 
movements  in  an  aquatic  medium — together  with  the  lateral  posi- 
tion of  its  eyes,  may  have  had  something  to  do  with  the  fact  of  the 
occurrence  of  a  decussation  of  the  budding  optic  tracts  in  some  of 
the  early  forms  of  Fishes. J 

*  "Brit,  and  For.  Med.  Chir.  Eeview,"  1866. 

f  Though  according  to  Siebold  an  exception  to  this  rule  is  to  be 
found  in  the  case  of  Bdellostoma,  one  of  the  Myxinoid  or  lowest 
class  of  Fishes. 

;|:  Marshall  ("  Outlines  of  Physiology,"  vol.  i.  p.  602)  endeavours 
to  account  for  this  one  primary  decussation  b}'-  supposing  it  to 
depend  upon  the  lateral  reversion  of  optic  images  occasioned  by 
the  concave  shape  of  the  retina  in  Fishes.  But  his  reasons  seem 
unsatisfactory,  because  with  a  similarly  shaped  retina  no    cross 


Chap.  XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN.  481 

5.  But  when  distinct  limbs  appear  in  higher  Reptiles,  and  when 
in  Birds  and  Mammals  the  movements  of  more  or  less  similar  limbs 
become  increasingly  volitional  and  independent  of  one  another,  two 
additional  results  might  be  expected  to  follow  the  primary  decussa- 
tion of  the  Optic  I^erves  (howsoever  this  may  have  been  deter- 
mined) : — (a)  those  other  *  sensory  '  channels  whose  impressions  are 
most  concerned  in  the  instigation  of  limb  movements  would  also 
tend  to  decussate,  because  it  would  be  very  essential  that  more  or  less 
unilateral  Tactile  and  Auditory  Impressions  should  be  brought  into 
relation  centrally  with  Yisual  Impressions  coming  from  the  same 
side  of  the  body;  (b)  coincidently  with  the  establishment  of  a 
decussation  of  the  '  sensory'  channels— and  especially  those  of  the 
Tactile  Sense  and  common  sensibility — in  animals  accustomed  to 
perform  unilateral  voluntary  movements,  we  might  expect  that 
there  would  be  a  tendency  to  the  establishment  of  an  answering 
cross-relation  between  the  '  motor '  channels  of  the  Cerebro-Spinal 
System.  Thus,  that  half  of  the  Brain  which  has  first  received  the 
instigating  sensorial  impressions  would  be  enabled  to  send  forth  the 
motor  stimuli — both  for  the  reflex  and  for  the  volitional  movements 
of  limbs  on  one  side  of  the  body.  And,  if  there  is  to  be  no  separate 
decussation  for  the  channels  of  reflex  and  volitional  motor  incita- 
tions  respectively,  such  crossings  of  motor  channels  as  we  find 
existing  in  the  Medulla  of  Man  and  many  other  Vertebrates  {i.e. 
at  the  '  decussation  '  of  the  Pyramids)  would  seem  to  be  the  only 
natural  arrangement. 

6.  This  more  complete  cross  arrangement  seems  only  to  be 
perfected  to  the  extent  indicated,  in  higher  Mammals  and  in 
Man. 

relation  exists  in  Cuttlefishes  ;  secondly,  because  there  is  no  evidence 
to  show  that  the  '  motor  '  channels  undergo  any  similar  decussation 
(though  this  hypothesis  assumes  its  existence)  in  the  lower  limbless 
Vertebrates,  in  whom  the  decussation  of  the  optic  tracts  becomes 
initiated  ;  and,  thirdly,  because  the  experience  of  workers  with  the 
microscope  tends  to  show  the  ease  with  which  adaptation  of  the 
movements  of  the  hands  to  meet  the  case  of  a  reversal  of  the  optic 
image — involving  as  it  does,  moreover,  a  reversal  of  upper  and 
lower,  as  well  as  of  lateral  parts— is  brought  about.  This  latter 
reason  helps  to  show  that  no  important  anatomical  changes  would 
be  needed,  as  Marshall  seems  to  suppose,  to  meet  the  case  of  a  mere 
reversal  of  the  optic  images. 


482  THE   FUNCTIONAL    RELATIONS    OF    THE 

7.  A.  cross  arrangement  of  sensory  channels  would  seem  to  be 
less  essential  in  the  case  of  Taste  and  Smell  than  for  either  of  the 
other  kinds  of  ingoing  impressions,  first,  because  the  organs  subser- 
vient to  these  endowments  are  situated  more  in  the  middle  line  of 
the  body  than  either  of  the  others ;  and,  secondly,  because  impressions 
of  Taste  and  Smell  are  perhaps  less  immediately  provocative  than 
those  of  other  senses,  of  unilateral  limb  movements.  The  nerves 
of  Taste  being,  however,  bound  up  with  or  forming  part  of  two 
nerves  of  common  sensibility  (the  Fifth  and  the  Glosso-pharyngeal) 
they,  as  it  were,  follow  the  lead  of  the  nerve  trunks  to  which  they 
belong,  and  decussate  with  them.  But  in  regard  to  Olfactory 
channels,  it  is,  as  matter  of  fact,  notable  that  they  are  the  only 
ones  in  which  no  decussation  is  known  to  occur,  either  in  the  lower 
animals  or  in  Man.  The  Olfactory  Centres  of  the  two  hemispheres 
are,  however,  very  amply  connected  by  means  of  commissural 
fibres — principally  gathered  together  in,  and  for  the  most  part  con- 
stituting, the  '  anterior  commissure.' 

Thus,  in  brief,  the  writer's  view  is  this:— That  the  cross  relation 
between  the  halves  of  the  Brain  and  the  body  may  have  been 
initiated  in  some  Fishes  in  a  quasi-accidental  manner,  and  that 
in  the  first  stage  of  its  existence  it  was,  and  still  is,  represented 
only  by  the  decussation  of  the  Optic  Tracts  ;  that  in  higher  animals 
possessed  of  well-formed  limbs  reflex  and  volitional  movements  of 
those  of  one  side  are  very  often  evoked  in  response  to  unilateral 
sensory  stimuli,  so  that  in  such  creatures  there  would  be  a  dis- 
tinct advantage  if  other  sensory  channels,  by  decussating,  were  to 
be  brought  into  relation,  at  their  central  termini,  with  those  of 
the  Visual  Sense ;  finally,  the  same  influences,  whatever  they  may 
be,  which  determine  this  additional  sensory  decussation,  would 
lead  to  an  establishment  of  the  equally  necessary  sequential  de- 
cussation of  the  motor  channels  for  the  limbs.  The  cross  arrange- 
ment of  sensory  and  motor  channels  met  with  in  Man  and  higher 
Mammals  is,  therefore,  to  be  regarded  as  an  almost  necessary 
sequence,  from  the  point  of  view  of  the  evoluticm  theory,  of  a 
primary  and  perhaps  quasi-accidental  decussation  of  the  Optio 
Tracts  in  Fishea. 


Chap.  XXIV.]         PRINCIPAL  PARTS  OF  THE  BRAIN.  483 

2.— The  Functional  Relations  of  the  Cerebral  Hemi- 
spheres with  one  another:  the  Duality  of  Body 
and  the  Unity  of  Mind. 

The  two  Cerebral  Hemispheres  are  now  generally 
admitted  to  contain  the  ultimate  prolongations  of  the 
*  ingoing '  nerves,  or  nerves  of  Sense,  and  to  be  constituted 
by  the  aggregation  of  the  organic  centres  (abundantly 
interconnected  by  '  commissural'  fibres)  of  all  those  higher 
mental  processes  which  we  have  traced  as  derivatives  of 
the  exercise  of  conscious  Sensibility,  viz.,  the  specially 
automatic  processes  of  Perception,  Ideation,  Emotion, 
Conception,  Reasoning,  together  with  the  more  volitional 
processes  of  Attention,  Recollection,  Imagination,  and 
Constructive  Thought.  The.  Cerebral  Hemispheres  con- 
tain, however,  in  addition  to  the  Sensory  Centres  and 
those  for  the  derivative  processes  above  indicated,  multi- 
tudes of  fibres  and  some  Centres  for  the  conduction  and 
proper  grouping  of  *  outgoing  '  currents. 

Of  the  various  transverse  commissures,  already  described, 
that  connect  these  parts  with  one  another,  one,  of  more 
importance  than  the  others,  now  deserves  some  further 
attention.  This  is  the  great  transverse  commissure,  or 
Corpus  Callosum,  which,  showing  itself  first  in  lower 
Mammals,  increases  in  size  in  higher  members  of  the 
series,  till  we  find  it  attaining  its  maximum  development 
in  the  brain  of  Man.  As  stated  in  the  last  chapter,  the 
fibres  of  the  Corpus  Callosum  pass  across  from  Hemis- 
phere to  Hemisphere,  so  as  to  bring  into  relation  corres- 
ponding areas  of  convolutional  Grey  Matter.  It  does 
not  pass  equally  between  all  convolutions,  but  especially 
between  those  which  are  also  in  relation  with  the  great 
basal  ganglia  (Broadbent).  The  Anterior  Commissure, 
though  a  morphologically  distinct  part,  seems  to  have  an 


484     THE  FUNCTIONAL  RELATIONS  OF  THE 

essentially  parallel  function,  since  its  fibres  also  serve  to 
connect  similar  convolutions  on  the  two  sides — viz.,  some 
of  those  situated  in  the  Temporal  Lobes.  A  similar 
function  must  also  be  assigned  to  the  *  Psalterial  Fibres,' 
which  in  part  constitute  the  posterior  bent  portion 
('  genu')  of  the  Corpus  Callosum  itself  (p.  443,  notef). 

These  transverse  'commissural'  fibres  are  of  much 
interest,  because  there  is  reason  to  believe  that  they  are, 
to  a  considerable  extent,  in  relation  with  that  unification 
of  Consciousness  which  unquestionably  exists  (as  everyone 
can  testify)  in  spite  of  the  fact  that  the  organs  of  Sensorial 
Activity  are  double  throughout.  Such  Commissures  are 
also,  in  all  probability,  very  essential  for  the  carrying  on 
of  the  higher  mental  processes.  In  cases  recorded  by 
Dr.  Langdon  Down  and  others  the  non-development  of 
this  part  of  the  Brain  in  human  beings  has  been  asso- 
ciated with  more  or  less  marked  Idiocy;  but  then,  the 
arrest  of  development  has  for  the  most  part  not  been  strictly 
limited  to  the  Corpus  Callosum.  The  Middle  Commis- 
sure, the  Fornix,  or  some  convolution al  regions  have  been 
often  at  the  same  time  deficient.  In  some  of  the  recorded 
cases  in  which  the  Corpus  Callosum  has  been  only  partially 
absent,  there  has  been  less  degradation  of  the  Intellectual 
Powers  than  might  have  been  anticipated.  In  certain  of 
these  latter  cases,  however,  the  persons  have  either  died 
so  young,  or  the  morbid  conditions  have  been  so  com- 
plicated, as  to  make  them  of  comparatively  little  value 
for  settling  the  question  as  to  the  real  importance  of  the 
Corpus  Callosum  in  the  carrying  on  of  mental  processes.* 

According  to  the  anatomical  data  furnished  by  Broad- 
bentf  it  is  the  Sensorial  Begions  of  the  two  hemispheres 

*  See  Knox,  in  "  Glasgow  Medical  Journal,"  April,  1875,  where 
6fteen  cases  are  referred  to. 
t  See  p.  442. 


Chap.  XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN.  485 

(or  the  Sensorial  and  what  some  regard  as  the  Vohtional) 
which  are  immediately  brought  into  relation  by  means  of 
the  Corpus  Callosum.  But  even  if  this  supposed  arrange- 
ment be  the  one  that  actually  exists,  it  would  by  no  means 
indicate  that  the  organic  seats  of  the  more  complex  deriva- 
tive processes  are  not  also  mediately  brought  into  relation 
with  one  another.  The  more  specialized  Emotional,  Intel- 
lectual, and  Volitional  Eegions  in  each  hemisphere,  wher- 
ever they  may  be,  and  however  they  may  be  related  to 
one  another,  are  necessarily,  by  means  of  the  *  association 
system '  of  fibres,  brought  into  intimate  comnmnion  with 
their  corresponding  Sensorial  Regions  of  various  kinds.  It 
is  in  this  indirect  w^ay,  therefore,  that  the  higher  functional 
regions  of  the  two  Hemispheres  may  be  brought  into  rela- 
tion wdth  one  another,  through  the  medium  of  the  fibres  of 
the  Corpus  Callosum.  There  is  manifestly  a  unity  in  our 
Emotional,  Intellectual,  and  Volitional — as  well  as  in  our 
Sensorial  Consciousness — that  is,  in  the  '  derivative  '  as 
well  as  in  the  '  primary  '  mental  processes. 

There  can  be  little  doubt  that  Sensorial  Activity  and 
the  action  of  those  portions  of  the  Brain  which  are  directly 
concerned  therewith,  affords  the  primary  or  essential  basis 
of  Consciousness.  We  are  most  fully  conscious  when 
we  are  most  receptive  of  external  impressions,  and  we 
lapse  into  a  completely  or  partially  unconscious  condition 
when  the  advent  of  such  impressions  is  for  a  time 
prevented,  or  when  we  are  intensely  absorbed  in  some 
train  of  thought  (Ideal  or  Reflective  Consciousness) — that 
is,  when  the  activity  of  other  portions  of  the  Cerebral 
Hemispheres  in  some  way  dwarfs  or  eclipses  that  of  the 
sensorial  regions  proper.  An  admirable  illustration  of  the 
former  truth  has  been  lately  given  by  Dr.   Striimpell,* 

*  "  Pfliiger's  Archiv,"  vol.  xv.  p.  573,  and  translated  in  "Nature," 

DecLiuber  13, 1877. 


i86  THE    rUNCTIONAL    RELATIONS    OF    THE 

which    is    so    instructive    as    to    be    worth    quoting   in 
full. 

"  In  the  autumn  of  last  year  there  was  received  into  the  medical 
clinic  of  Leipzig  a  youth  aged  16,  in  whom  various  phenomena  of 
anaesthesia  gradually  developed  themselves  to  an  extent  which  has 
v^ry  rarely  been  observed  The  skin  of  the  whole  surface  of  the 
body  was  completely  insensible,  and  that  in  respect  to  every  kind 
of  sensation.  The  most  powerful  electric  current,  or  a  burning  taper 
held  to  the  skin,  was  not  able  to  produce  any  pain,  or  even  a  sen- 
sation of  touch.  Almost  all  the  accessible  parts  of  the  mucous 
membrane  of  the  body  exhibited  the  same  insensibility  to  pain. 
Also,  all  those  sensations  which  are  classed  together  under  the 
name  of  'muscular  sense'  were  entirely  absent.  The  patient, 
when  his  eyes  were  closed,  could  be  carried  about  round  the  room, 
his  limbs  could  be  placed  in  the  most  inconvenient  positions,  with- 
out his  being  in  any  way  conscious  of  it.  Even  the  feeling  of 
muscular  exhaustion  was  lost.  In  addition,  there  came  on  also  a 
complete  loss  of  taste  and  smell,  amauroses  of  the  left  eye,  and  deaf- 
ness of  the  right  ear. 

In  short,  here  was  an  individual  whose  only  connection  with 
the  outer  world  was  limited  to  two  doors  of  sense — to  his  one 
(right)  eye  and  his  one  (left)  ear.  Moreover,  both  these  remaining 
doors  could  at  any  time  be  easily  closed,  and  in  this  way  it  was 
possible  to  investigate  the  consequences  of  completely  isolating  the 
brain  from  all  external  stimulation  through  the  senses.  I  have 
frequently  made  the  following  experiment,  and  often  showed  it  to 
others  : — If  the  patient's  seeing  eye  was  bandaged  and  his  hearing 
ear  was  stopped,  after  a  few  (usually  from  two  to  three)  minutes 
the  expression  of  surprise  and  the  uneasy  movements  which  at  first 
showed  themselves  ceased,  the  respiration  became  quiet  and  regu- 
lar ;  in  fact,  the  i^atient  was  sound  asleep.  Here,  therefore,  the 
possibility  of  artiticially  inducing  sleep,  at  any  time,  in  a  person 
simply  by  withholding  from  the  brain  all  stimulation  by  means  of 
the  senses  was  realized. 

The  awakening  of  the  patient  was  as  interesting  as  the  sending 
him  to  sleep.  He  could  be  awakened  by  an  auditory  stimulation, 
as,  for  example,  by  calling  into  his  hearing  ear,  or  by  visual  stimu- 
lation, by  allowing  the  stimulus  of  light  to  fall  upon  his  seeing 
eye;  but  he  could  not  be  wakened  by  any  pushing  or  shaking.  If 
he  was  left  to  himself  he  did  eventually  wake  up  of  his  own  accord 


Chap.  XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN.  487 

ill  course  of  the  day,  after  the  sleep  had  lasted  many  hours;  the 
awakening  being  due,  it  might  be,  to  intrinsic  stimuli  started  in 
the  brain,  or  it  might  be  to  slight  external  unavoidable  stimuli  act- 
ing through  his  still  functional  sense  organs,  and  making  them- 
selves felt  in  consequence  of  the  sensitiveness  of  the  brain  being 
increased  during  the  repose  of  sleep." 

Nothing  could  show  more  distinctly  than  such  a  case  as 
this  the  importance  of  the  activity  of  the  Sensorial  Kegions 
of  the  Hemispheres  for  the  production  of  what  we  know 
as  Consciousness.  It  seems  clear,  indeed,  that  if  Con- 
sciousness is  not  in  some  way  an  immediate  appanage  of 
the  activity  of  these  very  regions  of  the  Hemispheres, 
their  activity  is,  at  all  events,  an  essential  forerunner 
of  that  of  some  other  regions  between  whose  activity 
and  Consciousness  there  is  such  an  immediate  associa- 
tion. 

On  the  other  hand,  it  is  equally  clear  that  the  stimulat- 
ing sensorial  impressions  are  double,  coming  to  each 
Hemisphere  of  the  Brain  from  opposite  halves  of  the  body, 
and  that  their  subjective  accompaniments  are  merged 
into  a  single  Consciousness  of  this  or  that  kind.  The  final 
proof  of  this  position  is  afforded  by  the  effects  of  injury 
to  certain  portions  of  the  Brain  on  one  side  only  in  some  of 
the  lower  animals,  and  by  the  effects  of  unilateral  disease 
of  corresponding  regions  of  the  Brain  in  Man.  Thus,  where 
we  have  to  do  with  injury  or  with  disease  of  the  posterior 
third  of  what  is  known  as  the  '  internal  capsule ' — that  is, 
of  that  portion  of  the  expansion  of  the  Cerebral  Peduncle 
which  lies  between  the  posterior  part  of  the  Corpus  Stria- 
tum and  the  Thalamus — there  is  found  to  be  complete 
loss  of  sensibility  on  the  opposite  half  of  the  body  (Hemi- 
anaesthesia).  No  touch  can  be  felt,  and  all  the  other 
avenues  of  sense  on  this  side  are  similarly  closed — the 
tongue  and  side  of  the  mouth  are   dead  to  flavours,  the 


488     THE  FUNCTIONAL  RELATIONS  OF  THE 

ear  is  dead  to  sounds,  the  eye  is  blind,  and  the  correspond- 
ing nostril  is  similarly  insensitive  to  all  odours.* 

But  in  Hemi-anaesthesia,  although  the  avenues  of  sense 
are  dosed  on  one  side,  the  general  Consciousness  of  the 
individual  appears  to  remain  unaft'ected,  and  his  Mental 
Activity  may  be  but  little  impaired.  This  comparatively 
unaltered  mental  condition,  notwithstanding  the  absence 
of  direct  sensorial  stimulation  of  one  Hemisphere,  is  prob- 
ably possible  only  through  the  intervening  activity  of  the 
Corpus  Callosum — since  by  means  of  its  fibres  the  stimulus 
to  the  one  side  of  the  Brain  may  be  propagated  to  the  other. 
Both  Hemispheres  may  thus  be  brought  into  relation  with 
the  various  sensorial  stimuli  emanating  from  one  side  of  the 
body;  and  in  this  way  it  is  possible  for  the  general  Con- 

*  The  explanation  of  the  loss  of  the  sense  of  Smell  in  the  cor- 
responding nostril  presents  some  difficulties.  It  seems,  at  first 
sight,  to  be  altogether  at  variance  with  anatomical  facts,  since  the 
relations  of  the  organs  of  smell  with  the  hemispheres  are,  as  already 
pointed  out  (p.  4ti8),  exceptional.  They  are  certainly  direct  rather 
than  crossed,  and  it  would  also  tend  to  contradict  existing  ana- 
tomical knowledge  if  fibres  from  the  Olfactory  Ganglia  on  the 
road  to  their  '  perceptive  centres  '  were  to  be  found  anywhere  in  the 
neighbourhood  of  the  posterior  part  of  the  corona  radiata.  But  a 
very  plausible  explanation  of  the  loss  of  the  sense  of  Smell  in  these 
cases  of  Hemi-ansesthesia  is  to  be  found,  as  Dr.  Terrier  points  out 
("Functions  of  the  Brain,"  p.  191),  in  the  well-ivuown  experiments 
of  Magendie,  as  to  the  functions  of  the  fifth  nerve.  He  ascertained 
that  Smell  was  lost  when  the  sensibility  of  the  nostril  was  abo- 
lished— e._<7.,  after  the  fifth  nerve  had  been  cut;  not  because  the  fifth 
is  the  nerve  of  Smell  properly  so  called,  but  because  "  the  integrity 
of  the  fifth  is  necessary  to  the  due  functional  activity  of  the  olfac- 
tory nerves."  If  the  unilateral  loss  of  Smell  in  these  cases  of 
Hemi-ansesthesia  be  really  due  only  to  the  loss  of  common  sensi- 
bility in  the  corresponding  nostril,  then  the  same  loss  of  Smell 
ought  to  occur  in  Man  with  those  lesions  of  the  '  pons  Varolii '  in 
which  the  common  sensibility  of  one  side  of  the  body  is  annulled  : 
and  the  writer's  experience  leads  him  to  believe  that  this  loss  does 
occur  in  such  cases. 


Chap.  XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN. 


489 


sciousness  of  the  individual  to  remain  unaltered,  even  in 
the  ahsence  of  sensorial  stimuli  from  one  half  of  the  hody. 

It  is  most  important  to  recollect  that  the  results  above 
described  follow  lesions  of  the  posterior  third  of  the 
Cerebral  Peduncle,  just  before  its  fibres  come  into  rela- 
tion with  the  Thalamus.  The  effects  are  very  different 
when  lesions  exist  above  or  outside  the  great  '  basal  gan- 
glia '  (see  p.  493),  even  though  these  lesions  may  involve 
extensive  destruction  of  one  Hemisphere. 

It  is  only  in  the   sphere   of  the  three  higher   senses, 


Fig.  171.— Transverse  section  through  the  Cerebrum  of  i\  Dog  opposite  the  middle 
of  the  Thalami,  showing  the  portion  of  the  '  internal  capsule,'  the  section  of  which 
produces  Hemi-ansestliesia.  (Charcot  after  Buret.)  0,  0,  Thalami  connected  by 
Middle  or  Soft  Commissure  ;  P,  P,  posterior  third  of  Cerebral  Peduncle  ('  internal 
capsule  ').  On  the  right  side  these  fibres  are  represented  as  cut  across  at  x  ;  S,  intra- 
ventricular, and  L,  extra-ventricular  Corpus  Striatum. 

however,  that  a  blending  of  the  subjective  accompaniments 
of  impressions  from  the  two  sides  of  the  body  occurs,  so 
as  to  produce  single  Perceptions.  An  object  which  is 
smelt  is  perceived  as  one  ;  a  body  which  is  seen  is  recog- 
nized as  single  ;  and  similarly  a  sound,  though  stimulat- 
ing both  auditory  organs,  is  heard  as  one  sound.  And 
although  we  can  localize  gustatory  impressions  to  one  or 
other  side  of  the  mouth,  when  our  attention  is  directed  to 
the  subject,  we  are  not  accustomed  to  do  so,  and  there  would 


490  THE    FUNCTIONAL    RELATIONS    OF    THE 

be  little  use  in  making  such  discriminations.  The  case  is 
altogether  different,  however,  in  regard  to  the  sense  of 
Touch,  or  common  sensibility.  By  means  of  Smell,  Sight, 
and  Hearing  we  are  brought  into  relation  with  distant 
phenomena,  but  in  the  exercise  of  Taste  and  Touch  there 
is  actual  contact  with  different  portions  of  the  extended 
surface  of  our  bodies,  and  therefore,  in  the  latter  case  more 
especially,  there  ought  to  be,  as  there  is,  a  thoroughly 
independent  power  of  appreciating  the  impressions  im- 
pinging upon  each  side  of  the  body,  and,  indeed,  of  pretty 
accurately  localizing  them. 

This  unity  of  result  accompanying  the  action  of  a  great 
part  of  the  Sensorial  Regions  of  the  two  Hemispheres,  as 
well  as  in  those  which  are  subservient  to  Emotional  and 
Intellectual  Activity,  is  very  remarkable,  and  difficult  to 
understand,  especially  if  we  bear  in  mind  the  fact  that 
there  is  not  even  a  perfect  symmetry  in  the  naked  eye  con- 
format'on  of  many  of  the  homologous  Convolutions  of  the 
two  sides  (to  say  nothing  of  their  microscopical  structure) ; 
that  their  vascular  supply  is  independent,  and  therefore 
subject  to  variations  which  may  affect  one  side  only  ;  and 
that  an  inequality  of  working  power  on  the  two  sides  might 
also  easily  be  brought  about  by  some  inherent  or  acquired 
differences  in  the  molecular  (or  functional)  activity  of 
the  corresponding  nerve  elements  on  the  two  sides  of  the 
Biain. 

Notwithstanding  our  difficulty  in  comprehending  how  a 
double  mechanism  of  this  kind  can  work  as  it  does,  so 
as  to  lead  to  a  single  Consciousness,  or  so  as  to  enable  it 
to  carry  on  the  processes  of  a  single  Thinking  and  Willing 
personality,  the  facts  of  our  own  Consciousness  may  assure 
each  one  of  us  that  it  is  so. 

Yet,  though  it  may  be  the  rule  for  the  two  Hemispherea 


Chap.  XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN.  491 

to  be  called  into  simultaneous  and  harmonious  activity  in 
Perception,  Emotion,  Thought,  and  Volition,  evidence  is 
not  altogether  wanting  to  show  that  they  are  capable  of 
working  more  or  less  independently — either  {a)  where 
both  hemispheres  exist,  and  there  is  a  supposed  lack  of 
harmony,  with  resulting  '  double  Consciousness  '  ;  or  (h) 
in  the  more  positive  and  definite  cases  in  which  there  has 
been  no  impairment  of  Sense  or  Intellect  noted,  although 
the  greater  portion  of  one  Cerebral  Hemisphere  may  have 
been  destroyed.  On  each  of  these  subjects  a  few  words 
may  be  said. 

(a.)  The  evidence  in  favour  of  the  possibility  of  a 
separate  and  dissimilar,  though  simultaneous,  activity 
of  the  two  Hemispheres  of  the  Brain  is  of  a  very  doubt- 
ful nature,  though  there  are  facts  familiar  enough  to 
physicians  which  have  been  thought  to  support  this 
notion. 

The  question  was,  for  instance,  raised  by  Sir  Henry  Holland*  in 
1840, — "  Whether  some  of  the  aberrations  of  mind,  which  come 
under  the  name  of  insanity,  are  not  due  to  incongruous  action  of 
this  double  structure  [the  two  hemispheres], to  which  perfect  unity 
of  action  belongs  in  the  healthy  state  ?  "  He  adds  : — "  The  sub- 
ject is  very  obscure,  and  all  proof  of  difficult  attainment;  but  I 
think  it  more  probable  than  otherwise  that  such  inequality  may  be 
a  cause  of  some  among  the  many  forms  of  mental  derangement. 
.  .  .  .  It  has  been  a  familiar  remark  that  in  certain  states  of 
mental  derangement,  as  well  as  in  some  cases  of  hysteria  which 
border  closely  upon  it,  there  appear,  as  it  were,  two  minds ;  one 
tending  to  correct  by  more  just  perceptions,  feelings,  and  volitions, 
the  aberrations  of  the  other ;  and  the  relative  power  of  the  two 
influences  varying  at  different  times.  .  .  .  It  is  remarkable 
how  distinct  an  expression  to  this  effect  may  occasionally  be  had 
from  patients  themselves.  I  have  recently  seen  a  case  of  which 
the  most  marked  feature  was  a  frequent  and  sudden  outbreak  of 
passion  upon  subjects,  partly  real,  partly  delusive,  but  generally 

*  "  Medical  Notes  and  Reflections,"  •2ud  Ed.,  1840,  p.  172. 


492  TPIE    FUNCTIONAL    RELATIONS    OF    THE 

without  obvious  or  sufficient  reason  at  the  moment;  these  excesses 
attended  with  loud  screaminfjf,  execrations,  and  acts  of  violence  in 
striking  or  breaking  things  within  reach.  Here  the  patient  himself 
described  to  me  the  kind  of  separate  consciousness  he  had  when 
these  violent  moods  were  upon  him ;  his  desire,  but  feelings  of 
inability  to  resist  them  ;  his  satisfaction  when  he  felt  them  to  be 
passing  away.  It  was  a  painfully  exaggerated  picture  of  the 
struggle  between  good  and  ill." 

Notliing  much  more  definite  could  then  be  said  upon 
this  subject,  nor  has  there  since  been  any  appreciable 
advance  of  our  knowledge  in  regard  to  it.*  It  is,  of 
course,  possible  that  two  seemingly  simultaneous  states  of 
Mind  may  be  never  strictly  coincident  in  time,  so  that  in 
the  cases  to  which  reference  has  just  been  made,  there 
may  have  been  merely  a  rapidly  alternating  action  of  the 
organ  as  a  whole,  rather  than  a  simultaneous  independent 
action  of  the  two  hemispheres  of  the  Brain.  Some  of  the 
phenomena  of  dreams  present  precisely  the  same  difficul- 
ties— indeed  the  evidence  in  favour  of  a  double  Conscious- 
ness is  here  even  more  striking,  since  most  of  us  may  be 
able  to  add  our  ow^n  personal  experience  to  the  testimony 
of  others.  We  refer  more  especially  to  those  cases  in 
which  the  dreamer  appears  to  be  carrying  on  a  long  con- 
versation with  some  other  person ;  where  two  distinct  trains 
of  thought  are  being  evolved ;  and  where,  occasionally,  there 
may  be  evidence  to  show  that  the  whole  dream  has  been  so 
rapidly  produced  as  to  make  it  more  easy  to  explain  the 
phenomena  by  the  supposition  of  a  simultaneous  and  inde- 
pendent action  of  the  two  Hemispheres  than  by  an  alter- 
nating different  action  of  the  Brain  as  a  whole. f 

*  Dr.  Wigan's  work  on  "  The  Duality  of  the  Mind,"  1814,  is  a 
diffuse  and  by  no  means  well-arranged  contribution  dealing  with 
the  same  subject. 

t  The  consciousness  of  the  dreamer  may  be  distinguished  under 
the  name  of  Ideational  Consciousness,  from  the  ordinary  conscious- 


Chap.  XXIV.]         PRINCIPAL  PARTS  OF  THE  BRAIN.  493 

(b.)  If  we  look,  on  the  other  hand,  to  the  question  as 
to  wliat  amount  of  Intellectual  Power  is  possible  where 
one  Hemisphere  of  the  Cerebrum  has  been  very  much 
damaged  or  atrophied  ;  there  can  be  little  doubt  that,  as 
a  rule,  the  ps}'chical  powers  would  be  found  very  much 
blunted  or  paralyzed.  This,  however,  is  far  from  being 
universally  the  case,  for  there  are  instances  on  record  in 
which,  with  atrophy  or  extensive  disease  of  one  Hemisphere, 
the  Intellectual  Faculties  appeared  to  be  in  their  normal 
condition. 

Preservation  of  any  considerable  Mental  Power  when 
there  is  great  damage  to  one  Hemisphere  is,  however,  very 
rarely  met  with  when  the  damage  occurs  late  in  life.  It 
is  much  more  likely  to  be  encountered  when  the  disease  or 
damage  has  set  in  or  happened  in  early  childhood :  at  a 
time,  that  is,  when  the  growth  and  textural  development 
of  the  Brain  is  capable  of  undergoing  considerable  modi- 
fications that  may  fit  it  for  the  more  or  less  isolated 
activity  of  the  one  Hemisphere — which,  in  the  cases  sup- 
posed, may  be  almost  all  that  is  possible.  Such  an  early 
onset  of  the  disease  is,  indeed,  found  by  the  writer  to  have 
existed  in  many  of  the  best  authenticated  cases  belonging 
to  this  category.* 

Perhaps  the  most  remarkable  of  all  the  cases  of  this  sort  on 
record  is  one  which  was  observed  and  reported  by  Andral.  A  man, 
who  died  in  his  twenty-eighth  year,  had  a  fall  when  three  years 
old,  after  which  he  continued  paralyzed  on  the  left  side.  The  right 
hemisphere  of  the  brain  was  found  to  be  so  completely  atrophied 

ness  of  the  waldng  state.  In  each  case  the  sensorial  regions  of 
the  hemispheres  would  seem  to  be  the  initial  or  central  tracts  whose 
activity  is  roused — in  the  one  case,  by  real,  and,  in  the  other,  by 
revived,  sensorial  impressions. 

*  "  Atrophy  of  the  Left  Hemisphere."     New  Sydenham  Soc, 
vol  xi.  p.  153.     Several  cases  are  here  referred  to  by  S.  Van  der 
Kolk,  including  the  one  recorded  by  Andral. 
22 


494     THE  FUNCTIONAL  RELATIONS  OF  TEE 

that  a  great  part  of  the  '  pia  mater  '  on  this  right  side  formed  a  cysts 
in  which  not  a  trace  of  cerebral  matter  remained.  This  membrane 
constituted  the  upper  wall  of  a  large  cavity,  the  floor  of  which 
alone  was  formed  by  the  Thalamus,  the  Corpus  Striatum  and  all 
the  parts  on  a  level  with  these  two  bodies.  No  nervous  matter 
existed,  therefore,  above  the  level  of  the  great  ganglia  on  the  right 
side — and  yet  Andral  says: — "Get  individu  avait  re^u  de  I'edu- 
cation  et  en  avait  profite ;  il  avait  une  bonne  memoire;  sa  parole 
etait  libre  et  facile;  son  intelligence  etait  celle  du  commun  des 
homnies." 

Cases  of  a  similar  character  have  been  recorded  by 
Cruveilbier  and  others,  and  it  is  a  remarkable  fact  that 
there  has  been  not  only  a  preservation  of  such  an  amount 
of  Intellectual  Power,  as  to  have  given  the  appearance,  at 
all  events,  of  no  loss  in  this  direction,  but  that  the  special 
modes  of  Sensibility  (such  as  Sight  and  Hearing)  have 
not  be^n  abolished  on  either  side — there  has  been  no  uni- 
lateral Blindness  or  Deafness  even  although  the  greater 
part  of  the  opposite  Hemisphere  may  have  been  destroyed. 
This  preservation  of  the  special  senses,  in  such  cases,  the 
writer  has  elsewhere  endeavoured  to  explain  by  an  exten- 
sion of  Broadbent's  hypothesis  concerning  the  single  or 
double  activity  of  '  motor  '  centres,  to  the  problem  as  to 
the  conditions  regulating  the  single  or  combined  activity 
of  the  '  sensory  '  centres.* 

These  previously  recorded  cases  of  disease  of  the  greater  part  of 
one  Hemisphere  and  preservation  of  the  special  Senses  on  both  sides, 
stand  out  in  notable  contrast  with  the  more  recently  published  cases 
of  lesion  of  the  posterior  third  of  the  'internal  capsule'  in  which 
Jlemi-anccthesia  has  been  produced  (see  p.  489).  In  the  latter  class 
of  cases  there  is  a  limited  lesion  in  the  '  sensory  '  region  of  the  Cere- 
bral Peduncle  just  before  it  comes  into  relation  with  the  Thalamus; 
whilst  in  the  cases  in  which  there  is  little  or  no  impairment  of 
Sense  on  either  side  the  lesion  has  mostly  involved  the  frontal  and 
parietal  regions  of  the  Hemisphere  above  the  level  of  the  Thalamus 

*  "  Paralysis  from  Brain  Disease,"  1875,  p.  106. 


Chap.  XXIV.]         PRINCIPAL  PARTS  Of  THE  BRAIN.         495 

and  Corpus  Striatum,  and  perhaps,  therefore,  without  much  impli- 
cating the  convolutions  of  the  Temporal  Lobe,  which,  as  will  be 
shown  in  the  next  chapter,  appear  to  contain  centres  or  regions  of 
special  importance  for  sensory  perception.  These  latter  cases  are 
of  great  interest,  but  more  accurate  information  would  be  required 
before  we  could  safely  come  to  any  definite  opinion  in  regard  to 
them.  The  old  observations  were  not  made  or,  at  all  events,  were 
not  recorded  in  that  rigorously  precise  manner  which  the  impor- 
tance of  the  subject,  from  our  present  point  of  view,  clearly 
demands. 

But  whilst  our  *Will'  is,  like  our  Intellect,  single 
(although  it  is  the  product  or  accompaniment  of  the  ac- 
tivity of  a  double  organ),  we  are  here,  on  the  occasion  of 
its  exercise,  brought  to  the  turning  point  where  'mental* 
gradually  give  place  to  'non-mental'  phenomena. 

The  outcome  of  many  Volitions  is  to  be  found  in  mus- 
cular r,ontractions  and  relaxations,  and  the  mere  passage 
of  '  ontgoing  currents  '  has  no  conscious  accompaniment  of 
ary  kind.*  After  the  Wish  or  Desire  with  '  a  sense  of  effort' 
(which  together  seem  to  make  up  what  we  individually 
know  of  a  Volition — so  far,  that  is,  as  it  reveals  itself  to  us 
as  a  phase  of  Consciousness),  we  have  to  do  with  mole- 
cular currents  passing,  it  may  be,  through  several  sets  of 
fibres  and  cells,  but  having  no  conscious  side  whatever, 
and  apparently  lying  just  as  much  outside  the  sphere  of 
Mind  as  the  molecular  changes  in  the  muscle  which 
these  '  outgoing  currents  '  evoke. 

It  was  for  these  reasons  that,  in  an  earlier  chapter,  the 
writer  was  led  to  limit  the  sphere  of  Mind,  and  to  re- 
gard that  portion  only  of  the  Nervous  System  as  its 
organ  which  has  to  do  with  the  reception,  the  trans- 
mission, and  with  the  vastly  multiplied  co-ordinations  of 

*  On  this  subject  see  what  Sir  Wm.  Hamilton  says  in  his 
"  Lectures,"  vol.  ii.  pp.  391,  392 ;  also  in  his  "  Dissertations 
on  Reid,"  pp.  866,  867. 


496  THE    FUNCTIONAL    RELATIONS    OF    THE 

'ingoing  currents'  in  all  kinds  of  nerve  centres.  On  the 
other  hand,  we  were  led  to  regard  the  phenomena  of  the 
*  outgoing  current  '  as  non-mental,  and  the  regions  of  the 
nervous  system  concerned  therewith  as  not  strictly  con- 
stituting parts  of  the  '  Organ  of  Mind.' 

Certain  it  is  that  directly  we  pass  from  the  purely 
mental  side,  or  from  the  starting-points  of  a  Volition,  we 
find  two  main  pathways  by  which  its  associated  stimuli  (in 
the  form  of  molecular  movements),  may  pass  away  from 
the  cortex  of  the  Cerebral  Hemispheres  to  Muscles  on 
each  side  of  the  body. 

The  muscles  of  the  right  or  left  limbs,  or  such  groups 
of  them  in  other  parts  as  are  usually  called  into  action 
independently  of  their  fellows  on  the  opposite  side  of  the 
body,  receive  their  '  volitional '  stimuli,  as  we  have  stated, 
only  through  the  Cerebral  Hemisphere  of  the  opposite 
side.  But  bilaterally  situated  muscles  that  habitually 
act  together,  may  be  stimulated  indifferently  from  either 
Hemisphere  (Broadbent),  owing  to  the  existence  of  inti- 
mate commissural  connections,  binding  together  the  du- 
plicate Spinal  Centres  in  relation  with  such  muscles  so 
closely  as  to  make  each  pair  in  effect  one  Centre. 

A  highly  important  exception  to  this  latter  rule  seems 
to  exist,  however,  in  the  case  of  the  bilaterally  acting 
muscles  concerned  in  the  Articulation  of  Words — that  is, 
in  ordinary  Speech.  Usually  the  stimulus  that  passes 
over  from  the  Cortex  to  incite  these  muscular  acts  issues 
from  one  Cerebral  Hemisphere  only,  and  in  the  great 
majority  of  cases  the  Left  Hemisphere  is  the  source  of 
Buch  Speech-incitations.  The  proof  of  these  statements, 
and  further  particulars  in  regard  to  the  paths  of  outgoing 
stimuli  generally,  will  be  given  in  subsequent  chapters. 


iJHAF    XXIV.]  PRINCIPAL  PARTS  OF  THE  BRAIN.  497 

3.  The  Functional  Relations  of  the  Cerebellum  with 
the  Cerebral  Hemispheres  and  the  Spinal  Cord. 

We  pass  now  to  another  subject  of  surpassing  interest 
but  of  great  obscurity.  What  are  the  functions  of  the 
Cerebellum  ?  This  is  a  question  which  seems  most  simple, 
though  it  is  one  that  has  perplexed  physiologists  for 
over  two  centuries,  and  may  still  be  considered  to  hold  its 
place  as  a  thoroughly  unsettled  problem.  The  most 
varied  views  have  been  entertained  by  different  physiolo- 
gists on  the  subject. 

Willis  and  others  have  regarded  the  Cerebellum  as  the  principal 
regulative  centre  for  involuntary  movements  as  well  as  for  the 
functions  of  vegetative  life;  Foville  and.  others  have  regarded  it  as 
a'sensoriurn  commune,' or  principal  centre  for  ingoing  conscious 
impressions;  Gall  and  some  of  his  followers  looked  upon  it  as  an 
organ  chiefly  concerned  with  the  '  instinct  of  propagation '  or  the 
'sexnal  appetite  ';  Flourens,  Longet  and  others  have  taught  that 
the  Cerebellum  is  the  seat  of  a  faculty  for  co-ordinating  voluntaiy 
and  other  muscular  movements;  Lussana,  endeavouring  to  exphiin 
the  mode  in  which  it  co-ordinates  voluntary  movements,  makes  it 
the  seat  of  the  '  muscular  sense';  Reil,  Rolando,  and  some  modern 
writers,  such  as  Luys,  Weir-Mitchell  and  others,  have  regarded  the 
Cerebellum  as  an  organ  for  engendering  and  distributing  the  nerve- 
force  needed  for  the  instigation  of  all  kinds  of  movements,  and 
even  for  stimulating  other  non-motor  nerve  centres.  This  by  no 
means  exhausts  the  list  of  views  which  have,  at  one  time  or  another, 
been  held  concerning  the  functions  of  the  Cerebellum.  Other  no- 
tions in  regard  to  this  organ  will,  indeed,  be  referred  to  in  subse- 
quent pages. 

How  are  we  to  choose  from  amongst  these  bewilderingly 
different  theories  ?  Yulpian,*  after  carefully  reviewing 
the  whole  subject  in  1866,  felt  unable  to  accept  any  one 
of  them.  He  contented  himself  in  the  main  by  drawing 
certain  negative  conclusions.  ''  The  Cerebellum,"  ho 
*  "  La  physiolog.  du  Syst,  Nerveux,"  pp.  601-641. 


498  THE    FUNCTIONAL    RELATIONS    OF    THE 

Baid,  **  takes  no  part  in  cerebral  functions  proper.  It 
appears  to  have  nothing  at  all  to  do  with  the  manifesta- 
tions of  Instinct,  of  Intelligence,  or  of  Will.'*  Whether 
absolutely  correct  or  not,  this  is  a  notion  commonly  enter- 
tained. On  the  other  hand,  that  certain  ataxic  disorders 
of  movement  are  caused  by  lesions  of  the  Cerebellum, 
Vulpian  felt  compelled  to  admit ;  though  he  rejected  the 
commonly  entertained  hypothesis  of  Flourens,  that  it  is 
**  a  centre  by  which  the  co-ordination  of  voluntary  and 
other  movements  is  eiFected." 

The  great  uncertainty  that  has  always  prevailed  in 
regard  to  the  functions  of  the  Cerebellum  is  due  to 
various  causes.  It  is  attributable  partly  to  the  com- 
plicacy of  the  connections  of  this  organ  with  other  regions 
of  the  central  Nervous  System,  as  well  as  to  the  obscurity 
w^hich reigns  as  to  the  several  sources  of  its  'ingoing,'  and 
the  destination  of  its  '  outgoing,'  fibres — for  to  suj)pose 
with  Luys  that  the  peduncles  of  the  Cerebellum  are  com- 
posed of  *  outgoing '  fibres  only  seems  to  the  writer  as 
opposed  to  fact  as  it  would  be  to  the  plan  of  Nerve 
Centres  generally.  But  the  uncertainty  as  to  the  real 
functions  of  this  organ,  is  due  also  to  the  variety  and 
obscurity  of  the  symptoms  resulting  from  its  injury  in 
any  of  the  lower  animals,  and  from  a  like  variability  of 
relation  between  symptoms  and  lesions,  revealed  to  those 
who  study  the  effects  of  diseases  of  the  Cerebellum  in  Man. 

These  latter  variations  are  attributable  partly  to  the  intimate 
connection  of  the  Cerebellum  with  other  important  portions  of  the 
Brain.  This  makes  it  difficult  to  experiment  with  the  organ  in  tlie 
lower  animals  without  great  risk  of  irritating  or  injuring,  now  one, 
now  another  of  these  adjacent  parts;  and  equally  difficult,  on  the 
other,  to  get  nncomplicated  disease  of  the  (Cerebellum  — disease  that 
is  limited  to  this  organ  and  unassociated  with  symptoms  resulting 
from  pressure  on,  or  irritation  of,  other  important  parts,  such  as  the 
Medulla  or  *  pons  Varolii.* 


CaAP.  XXIV.]         PRINCIPAL  PARTS  OF  THE  BRAIN.  499 

But  the  effects  of  the  foregoing  sources  of  uncertainty  are  pro- 
bably increased  by  what  we  shall  find  to  be  the  well-grounded  con- 
sideration, that  the  Cerebellum,  whatever  may  be  the  precise 
nature  ot  its  functions,  does  not  commonly  act  alone,  but  to  a  very 
considerable  extent  in  conjunction  with  the  Cerebrum  in  the  per- 
foruiance  of  certain  functions  common  to  both.  Thus  it  seems 
not  at  all  unlikely  that  in  cases  of  injury  or  disease  of  the  Cere- 
bellum there  may  be  some  compensatory  increased  action  of  the 
Cerebrum — especially  where  the  disease  has  lasted  long  or  has 
commenced  at  an  early  age,  as  in  the  case  of  atrophy  of  this 
organ  in  the  girl  examined  by  Combette,  and  whose  case  is  re- 
corded by  Cruveilhier.  Lastly,  another  cause  of  difficulty,  tending 
to  complicate  the  interpretation  of  the  results  of  disease  of  the 
Cerebellum,  may  arise  from  the  possibility  that,  in  the  case  of  uni- 
lateral lesions,  the  sound  half  of  the  organ  may  be  capable  of 
taking  on  and  discharging  after  a  fashion — perhaps  with  a  mere 
difference  in  degree — the  functions  of  the  disabled  part  (see  p.  509, 
note). 

In  the  face  of  all  these  difiiciilties  of  interpretation  it 
may  be  well  to  turn  back  and  look  at  the  problem  as  to 
the  functions  of  the  Cerebellum  by  the  light  of  general 
principles,  aided  by  any  additional  illumination  which  we 
may  be  capable  of  obtaining  from  our  modern  knowledge 
(so  far  as  it  goes),  as  to  the  precise  anatomical  connec- 
tions of  the  organ  with  different  parts  of  the  Cerebrum 
and  with  different  tracts  of  the  Spinal  Cord. 

The  Cerebro-Spinal  System  of  Vertebrates  contains  a  series  of 
*  sensory  '  and  *  motor '  ceiitres  throughout  the  whole  length  of  the 
Spinal  Cord  and  Medulla,  each  of  which,  whilst  capable  of  per- 
forming independent  functions,  is  also  in  subordinate  relation  with 
other  higher  Nerve  Centres. 

Something  similar  obtains  among  Worms  and  Arthropods. 

But  the  Brain  in  all  Vertebrates  differs  from  that  of  Invertebrates, 
in  the  fact  that  it  possesses  two  double  morphologically  distinct 
parts,  unrepresented  among  the  latter,  or,  at  least,  unrepresented 
by  similarly  separable  parts.  These  are  the  Cerebral  Lobes  and 
the  Cerebellum.  Making  their  appearance  as  comparatively  small 
Begments  in  Fishes,  their  relative  size  and  development  increases 


600     THE  FUNCTIONAL  RELATIONS  OF  THE 

among  higher  Vertebrates,  so  as  at  last  to  throw  all  other  divisions 
of  the  Brain  into  the  shade. 

There  are,  therefore,  in  Vertebrates  some  fundamental  specializa- 
tions of  function,  which  are,  in  all  probability,  carried  much  larther 
than  in  any  of  the  lower  animals,  the  existence  of  which  seems  to 
become  marked  by  the  development  of  parts  so  distinct  morpho- 
logically as  the  Cerebral  Lobes  and  the  Cerebellum. 

But  it  is  to  be  regarded  as  one  of  the  best  established  of  physio- 
logical facts  that  the  Cerebral  Hemispheres  or  Lobes  are  the 
principal  organs  of  Conscious  Intelligence — including  under  this 
term  Sensation  and  Perception,  Ideation  and  Eeasoning,  together 
with  the  primary  phenomena  of  Emotion  and  Volition.  The  two 
Hemispheres  together,  therefore,  constitute  the  supreme  organ,  the 
last  term  of  the  series  of  centres,  in  which  'ingoing'  impressions 
are  brought  into  relation  with  one  another. 

But  two  things  are  now  almost  equally  certain  in  regard  to  the 
Cerebellum;  first,  that  it  has  no  appreciable  share,  as  an  indepen- 
dent organ,  in  the  carrying  on  of  any  of  these  processes  which,  in 
their  totality,  are  comprised  under  the  head  of  Conscious  Intelli- 
gence; and,  secondly,  that  its  activity  is  unmistakeably  mixed  up 
in  some  ivay  with  the  animal's  power  of  executing  Movements."* 
In  what  precise  manner  it  is  related  to  the  execution  of  Move- 
ments, and  to  what  Movements  it  is  so  related,  are  the  problems 
principally  requiring  to  be  solved,  and  to  these  subjects  we  must 
now  turn  our  attention. 

If  we  look  then  to  the  fact  that  throughout  the  ISTervous  Systems 
of  lower  animals  'sensory'  and  'motor'  nerve  centres  exist  in  corre- 
lated pairs;  if  we  look  to  the  simultaneous  appearance  of  the 
Cerebral  Lobes  and  the  Cerebellum  in  the  animal  series ;  if  we  con- 
sider that  the  Cerebral  Lobes  or  Hemispheres  have  been  proved 
to  be  the  supreme  centres  for  'ingoing'  impressions;  and  if  the 
Cerebellum  has  been  almost  equally  well  proved  to  be  a  great 
*motor'  centre  of  some  kind,  it  seems  a  fairly  legitimate  inference 
from  the  foregoing  facts  that  the  Cerebellum  is  the  supreme  motor 
centre  co-ordinate  with  the  Cerebrum,  and  that    they    form    the 

*  See  Owen,  "  Anat.  of  Vertebrates,"  vol.  i.  pp.  487,  488.  The 
hypothesis  of  Gall,  that  the  Cerebellum  is  the  seat  of  the  '  sexual 
instinct,'  has  little  or  nothing  to  be  said  in  its  favour  which  may 
not  be  otherwise  much  better  explained  (see  '  Ferrier's  Functions 
of  the  Brain,"  p.  122). 


Chap.  XXIV.]         PRINCIPAL  PARTS  OF  THE  BRAIN.  501 

final  'sensory'  and  'motor'  couple,  organized  or  attuned  to  some 
extent,  like  inferior  couples,  for  conjoint  activity. 

It  may,  however,  be  at  once  acknowledged  that  the  relation 
between  these  supreme  ingoing  and  outgoing  centres  in  Man  and 
higher  animals,  must  necessarily  be  very  different  and  much  more 
complex  than  that  existing  between  lower  couples  in  the  same 
animals,  or  than  that  existing  between  the  higher  couples  of 
such  animals  as  a  Centi]pede,  a  Gasteropod  (fig.  27)  or  any  other 
Invertebrate. 

The  relations  between  ingoing  impressions  and  responsive  actions 
through  the  intervening  activity  of  lower  centres  in  Man,  or  the 
higher  centres  of  a  lower  animal,  are  comparatively  simple  and 
direct;  but  in  higher  animals,  just  as  the  organ  of  Conscious  In- 
telligence increases  in  internal  complexity  and  bulk,  so  do  the 
chances  increase  of  the  intervention  of  complicated  nervous  pro- 
cesses between  the  reception  of  certain  Sensorial  Impressions  and 
any  actions  which  may  ultimately  result  therefrom.  The  acts 
that  follow  in  such  a  case,  as  a  result  of  'deliberation,'  ma}'-  be 
of  a  new  and  unaccustomed  order — consciously  conceived  and 
instigated. 

As  Sensorial  Consciousness,  and  the  Intelligence  that 
grows  out  of  its  exercise,  increases  in  intensity  and  com- 
plexity, this  side  of  life  becomes  all  engrossing  and  the 
Consciousness  of  the  animal  (or  its  Attention)  is  proportion- 
ately diverted  from  its  Visceral  Sensations  and  Movements, 
as  well  as  from  the  greater  part  of  the  multitudinous  '  auto- 
matic '  and  '  secondary-automatic '  Movements  concerned 
with  its  external  life,  or  'Life  of  Eelation.'  The  *area' 
of  Consciousness  is  limited  in  one  direction  and  widened  in 
another,  and  new  acquirements  would  never  be  made, 
either  in  the  sphere  of  Sense,  of  IntelligeDce  or  of  Volun- 
tary Movement,  unless  habitual  and  ever  recurring  Impres- 
sions might  of  themselves  (without  engaging  our  Con- 
sciousness) evoke  related  Movements — that  is,  unless  these 
latter  could  be  executed  and  regulated  under  the  super- 
intendence of  some  great  centre  in  response  to  mere  '  unfelt ' 
Impressions.      Thus  it  becomes  obvious  that  it  would  be 


602     THE  FUNCTIONAL  RELATIONS  OF  THE 

highly  advantageous,  if  not  absolutely  necessaiy,  for 
animals  in  whom  Conscious  Intelligence  obtains  a  high 
development,  that  their  principal  motor  centre,  the  Cere- 
bellum (and,  for  the  present,  we  assume  it  to  be  some 
such  organ),  should  be  in  relation  with  the  various  '  in- 
going' nerves  of  the  body  and  with  their  corresponding 
nerve  centres,  from  the  lowest  to  the  highest — or,  at  all 
events,  from  some  of  the  lower  to  the  highest. 

By  its  connection  with  the  highest  '  sensory '  centres, 
namely,  those  of  the  cortical  grey  matter  of  the  Cerebrum, 
the  Cerebellum  would  be  enabled  (a)  to  take  part  in  Volun- 
tary and  all  other  Movements  which  follow  (immediately  or 
remotely)  the  instigation  of  Conscious  Impressions ;  and 
by  its  connection  with  lower  centres  of  different  grades, 
it  would  be  enabled  (h)  at  the  instigation  of  *  unfelt ' 
Impressions,  to  take  a  much  larger  share  in  the  production 
and  maintenance  of  complex  '  automatic '  and  '  secondary- 
automatic  '  Movements  generally — just  such  a  share,  in 
fact,  as  the  lower  spinal  motor  centres  take  in  the  execu- 
tion of  spinal  '  reflex '  Movements.* 

The  mechanism  of  Voluntary  Movements  will  be  subse- 
quently referred  to.  It  is  only  needful  here  to  point  out 
that  *  Volition '  proper  is  inseparable  from  Sensorial 
Activity,  Intelligence,  and  Reason,  so  that  the  starting 
points  of  Volitional  '  stimuli '  must  be  somewhere  in  the 

*  In  an  animal  like  the  Frog,  in  which  the  Cerebellnni  is  very 
small  and  ill-developed,  even  movements  of  locomotion  are  capable 
of  being  executed  under  the  guidance  of  the  Spinal  Cord  alone.  It  is 
very  surprising  to  find  that  a  Frog,  whose  Cerebrum  and  Cerebellum 
have  been  destroyed,  can  still  stand,  and  even  leap.  It  is  surpris- 
ing, that  is,  if  we  look  at  it  from  the  point  of  view  of  what  would 
hapj)en  to  one  of  the  higher  animals  under  similar  circumstances, 
but  much  less  so  if  we  consider  the  degree  and  kind  of  locomotor 
powers  that  would  be  possessed  by  many  Insects  similarly  muti- 
lated. 


Cii.»p.  XXIV.]  PRINCIPAL  PAPvTS  OF  THE  BRAIN.  503 

organ  of  Conscious  Intelligence,  viz,,  the  Cerebrum.  It 
is  the  *  Actuation,*  or  carrying  into  effect  of  a  Volition 
destined  to  issue  in  Movement,  which  devolves  upon 
Motor  Centres,  and  there  is  reason  to  believe  that  the 
Cerebellum  co-operates  with  the  Corpora  Striata  in  the 
realization  of  this  secondary  part  or  phasis  of  an  ordinary 
Volitional  Act  and  its  consequence. 

Two  principal  questions  present  themselves,  therefore, 
as  a  result  of  what  has  been  hitherto  said  concerning  the 
probable  functions  of  the  Cerebellum.  (1)  What  evidence  is 
there  to  show  that  the  Cerebellum  is  largely  concerned  in 
the  production  of  '  automatic  '  and  '  secondary-automatic  ' 
Movements  in  response  to  'unfelt'  Impressions  ?  (2)  What 
evidence  is  there  to  show  that  the  Cerebellum  is  con- 
cerned in  the  execution  of  Voluntary  Movements  ? 

The  answers  to  these  questions,  so  far  as  they  can  be 
given — and  that  by  way  of  suggestion  rather  than  as 
positive  affirmations — may  be  best  set  forth  in  connec- 
tion with  some  statements  as  to  what  is  known  of  the 
composition  of  the  several  Peduncles  of  the  Cerebellum. 

There  is  reason  to  believe  that  it  is  principally  through 
the  intervention  of  the  Upper  and  Lower  Peduncles  that 
the  Cerebellum  receives  impressions  of  an  unconscious 
order,  which  enable  it  to  take  part  in  the  production 
of  certain  responsive  '  automatic '  and  '  secondary-auto- 
matic' Movements. 

The  reasons  in  favour  of  this  view  are,  first,  that  the  Upper  and 
Lower  Peduncles  contain  many  different  kinds  of  '  ingoing '  fibres, 
although  it  has  been  abundantly  proved  that  the  Cerebellum  is  in 
no  sense  an  organ  of  Conscious  Intelligence;  secondly,  it  is  sup- 
ported by  the  fact  that  in  Fishes  and  Reptiles  these  Peduncles 
alone  exist — the  Middle  Peduncles,  and  with  them  the  'pons 
Varolii,'  being  notoriously  absent.  For  it  it-  reasonable  to  suppose 
that  the   mere  'automatic'    or  '  sensori-motor  '   functions   of   the 


504  THE    FUNCTIONAL    RELATIONS    OF   THE 

Oerebellnm  would  be  established  earlier  than  those  in  relation  with 
Voluntary  Actions,  in  animals  in  whom  the  former  class  of  Move- 
ments are  much  more  frequent  and  numerous  than  the  latter. 

To  suppose  that  the  ingoing  (or  *  sensory ')  fibres  of  the  Cere- 
bellum merely  convey  to  this  organ  incitations,  which  cause  certain 
ganglionic  elements  in  its  cortical  Grey  Matter  to  '  discharge ' 
themselves  along  definitely  correlated  outgoing  fibres  (so  as  to 
arouse  various  lower  Motor  Centres  in  particular  modes  of  com- 
bination), enables  us  to  account  for  the  sensory  relations  of  the 
Upper  and  Lower  Cerebellar  Peduncles  without  looking  upon  the 
Cerebellum  itself  as  a  kind  of  '  sensorium  commune ' — as  it  was 
erroneously  regarded  by  Foville  and  others.*  If  it  is  to  minister 
to  the  execution  of  *  automatic '  Movements,  instigated  by  all 
kinds  of  '  ingoing '  Impressions,  it  is  obvious  that  it  must  be 
brought  into  relation  with  these  (perhaps  mainly  through  'inter- 
nuncial '  fibres),  though  it  is  not  at  all  necessary  that  the  incidence 
of  such  Impressions  upon  the  Cerebellum  should  be  attended  by 
any  phases  of  Consciousness. 

Lower  motor  centres  in  the  Spinal  Cord  are  in  immediate  rela- 
tion, through  *  internuncial '  fibres,  Trith  corresponding  sensory 
centres.  The  Cerebellum  would  seem  also  to  be  in  relation  with 
multitudes  of  fibres  of  this  type  reaching  it  from  more  or  less 
distant  '  sensory '  centres  of  difi'erent  kinds.  There  is  no  more 
reason,  however,  in  consequence  of  such  a  relation,  for  attributing 
*  sensory'  functions  to  the  Cerebellum,  than  there  would  be  for 
attributing  similar  functions  to  the  grey  matter  in  the  anterior 
horns  of  the  Spinal  Cord.  Such  relations  with  '  sensory  '  nuclei 
or  centres  are  indispensable  for  a  Motor  Centre,  whether  its  position 
be  high  or  low  :  only  the  higher  it  is  the  more  numerous  are  these 
connections  likely  to  be. 

Although  some  of  the  facts  concerning  the  connections  of  the 
Cerebellum  with  *  ingoing '  nerves  have  been  better  suljstantiated 
in  the  Brains  of  lower  Vertebrates  than  in  that  of  Man,  they  are 

*  Or  without  having  recourse  to  any  such  hypothesis  as  that 
of  Herbert  Spencer  ("  Principles  of  Psychology,"  vol.  i.  p.  61),  to 
the  effect  that  "  the  Cerebellum  is  an  organ  of  doubly-compound 
co-ordination  in  space,"  concerned  with  the  co-ordination  of  co- 
existent Impressions  and  Acts,  just  as  the  "  Cerebrum  is  an 
organ  of  doubly-compound  co-ordination  in  time,"  and  therefore 
concerned  with  sequential  Impression.s  and  Acts. 


Chap.  XXIV.]         PRINCIPAL  PARTS   OF   THE   BRAIN.  505 

scarcely  less  valuable  or  suggestive  on  this  account,  since  the  func- 
tions of  the  Cerebellum,  like  its  ultimate  structure,  are  probably 
uniform  in  kind  throughout  all  classes  of  the  Vertebrata. 

By  means  of  the  Upper  Peduncles  there  is  good  reason  to  believe 
that  the  Optic  Lobes  of  Fishes  are  brought  into  immediate  relation 
witli  their  rudimentary  Oerebellum.  The  fibres  constituting  these 
peduncles  pass  from  the  septum  between  the  Optic  Lobes  to  the 
median  portion  of  the  Cerebellum.  In  Man  the  same  peduncles, 
starting  from  the  '  red  nucleus '  in  the  sensory  tract  of  the  Crus, 
decussate  beneath  the  Corpora  Quadrigemina,  and  thence  proceed 
in  a  slightly  divergent  direction  to  the  anterior  portion  of  the  Cere- 
bellum. It  is  highly  probable,  therefore,  that  in  Man  also  these 
Upper  Peduncles  in  part  serve  to  bring  the  Optic  Centres  into  rela- 
tion with  the  Cerebellum. 

Again,  according  to  Meynert,*  a  portion  of  the  great  root  of  the 
Fifth  Nerve  or  '  Trigeminus,'  lies  on  the  upper  and  outer  border  of 
this  Upper  Peduncle,  and  a  portion  of  the  root  of  the  Auditoi-y 
Nerve  is  similarly  disposed.  In  some  Fishes  the  ganglion  at  the 
root  of  the  Fifth  Nerve  is,  according  to  Owen,  directly  connected, 
by  means  of  some  vertical  fibres,  with  the  Cerebellum. 

Thus,  though  almost  nothing  is  known  as  to  any  relations  of  the 
Olfactory  Lobe  with  the  Cerebellum,  it  seems  certain  that  the  next 
three  sensory  cranial  nerves  (viz.,  the  Optic,  the  Fifth  and  the  Au- 
ditory) come  into  relation  with  the  Cerebellum  through  its  Upper 
Peduncles. 

But  it  seems  possible  that  the  various  cortical  '  Perceptive  Cen- 
tres'  in  the  Cerebral  Hemispheres,  may  also  be  brought  into  rela- 
tion with  the  Cerebellum,  by  internuncial  fibres  passing  through 
the  'red  nucleus'  of  the  Tegmentum  and  the  Upper  Cerebellar 
Peduncles.  In  such  a  case,  these  fibres  might  convey  '  afferent ' 
stimuli  in  relation  with  Ideo-Motor  and  Voluntary  Movements, 
whilst  those  coming  to  it  from  Sensory  Nerves  or  their  Ganglia 
may  convey  'afferent'  stimuli  capable  of  evoking  movements  which 
have  become  '  automatic '  or  which  are  of  the  '  secondary-automatic  ' 
order.  Other  fibres,  however,  next  to  be  referred  to,  seem  also  to 
belong  to  this  latter  category.  Whether  the  Upper  Peduncles  con- 
tain afferent  fibres  only,  we  have  no  means  at  present  of  deciding. 

Each  Lower  Peduncle  of  the  Cerebellum  in  Fishes  is  in  close 
relation  with  the  two  '  visceral '  sensory  nerves,  viz.,  the  Vagus  and 
*  Strieker's  "Histology,"  vol.  ii.  p.  460. 


506     THE  FUNCTIONAL  RELATIONS  OF  THE 

Glosso-pharyngeal,  and  also  with  the  great  '  lateral  nerves,'  which 
are  usually  tributaries  to  the  second  root  of  the  Yagus.  The 
whole  of  this  latter  root  enters  the  Lower  Peduncle  just  below,  or 
by  the  side  of,  the  Cerebellum.  This  relation  is  not  so  distinct  in 
some  other  Vertebrates,  though  in  all  of  them  the  roots  of  the 
Vagus  are  in  close  relation  with  the  Lower  Peduncle  (or  *  restiform 
body  ').  There  is,  moreover,  good  reason  for  believing  that  the 
great  majority  of  the  fibres  of  these  Peduncles  are  afferent  fibres, 
which  come  (perhaps  by  a  doubly  decussating  course  through  the 
Spinal  Cord  and  Medulla)  from  Viscera,  Muscles  and  Skin,  on  the 
same  side  of  the  body — instead  of  entering  them  directly  like  the 
great  *  lateral  nerves '  or  the  Vagus  itself. 

But  in  addition  to  sensory  nerves  from  internal  and  external 
parts  of  the  body  generally,  the  Lower  Peduncles  of  the  Cerebellum 
also  transmit  to  this  organ  numerous  fibres  of  the  Auditory.  This 
arrangement  obtains  in  Man  as  well  as  in  lower  Vertebrates. 

In  reference  to  the  views  of  Cyon  (p.  218),  that  there  are  two 
distinct  nerves  included  under  what  is  commonly  known  as  the 
Auditory,  it  is  not  without  interest  to  find  some  of  its  fibres  going 
to  the  Cerebellum  by  the  Upper,  and  others  by  the  Lower  Peduncle. 
The  extensive  connections  of  this  double  nerve  with  the  Cerebellum 
are  also  of  considerable  interest,  in  view  of  the  relations  of  analo- 
gous nerves  in  the  majority  of  Mollusks  (and  in  such  Insects  as 
they  are  known  to  exist)  with  their  principal  motor  centres. 

It  seems  quite  certain  that  each  Lower  Peduncle  of  the  Cerebellum 
also  contains  some  efi"erent  or  outgoing  fibres,  and  that  these  (though 
probably  existing  also  in  other  parts)  are  gathered  into  a  snuiU 
fasciculus  (first  described  by  Solly),  which  passes  over  the  outer 
border  of  the  corresponding  Peduncle,  and  thence  sweeps  round 
the  lower  extremity  of  the  'olivary  body'  to  join  the  anterior 
column  of  the  Cord  just  above  the  'decussation '  of  the  Pyramids. 

There  is  reason  to  believe  that  it  is  through  the  interven- 
tion of  the  Middle  Peduncles  that  the  Cerebellum  princi- 
pally co-operates  with  the  Cerebrum  in  the  actual  execution 
of  Vt)luntary  Movements — though  its  incitations  to  take 
part  in  these  movements  may  also  come,  as  we  have 
already  suggested,  from  the  '  perceptive  centres '  in  the 
Cerebral  Hemispheres,  by  way  of  the  *  red  nucleus  '  and 
the  Upper  Peduncles. 


Chap.  XXIV.]         PRINCIPAL  PARTS  OF  THE  BRAIN.  507 

The  fact  that  the  Cerebellum  does  co-opera^^e  with  the 
Cerebrum  in  some  way  is  clear,  because  it  has  been 
proved  that  atrophy  of  one  Cerebral  Hemisphere  leads 
to  atrophy  of  the  opposite  half  of  the  Cerebellum.*  And 
that  the  Cerebellum  responds  to  stimuli  from  the  Cere- 
brum, rather  than  vice  versa,  seems  shown  by  the  fact 
that  atrophy  of  one  half  of  the  Cerebellum  has,  on  the 
other  hand,  no  tendency  to  cause  atrophy  of  the  opposite 
hemisphere  of  the  Cerebrum. 

The  notion  that  the  Middle  Peduncles  are  the  parts  by  which  the 
relation  between  the  Cerebrum  and  the  Cerebellum  is  principally 
brought  about  in  Yolitional  Action,  is  strongly  supported  by  two 
sets  of  facts;  first,  by  the  later  development  of  these  Middle 
Peduncles  and  of  the  lateral  lobes  of  the  Cerebellum  with  which 
they  are  principally  connected  in  the  animal  series,  as  well  as  by 
their  progressive  increase  in  still  higher  animals,  and  by  their 
maximum  size  in  Man;t  secondly,  the  view  is  also  borne  out  by 
what  we  know  of  their  anatomical  relations.  Broadbent's,  as  well 
as  Meynert's,  descriptions  give  us  some  warrant  for  believing  that 
fibres  pass  from  each  Middle  Peduncle  of  the  Cerebellam  to  the 
opposite  half  of  the  '  pons  Varolii,'  and  thence  (by  way  of  the  Crus 
Cc-rebri)  in  part  direct  to  the  cortex  of  the  Hemisphere,  and  in  part 
to  the  Corpus  Striatum  only.  Other  of  its  fibres  may,  perhaps, 
pass  down  to  motor  centres  in  the  Pons  itself,  or  to  similar  centres 
in  the  Medulla.;]; 

*  That  is  when  the  atrophic  process  of  the  Hemisphere  in- 
volves such  parts  as  to  entail  a  Hemiplegia — or  paralysis  of  the 
opposite  side  of  the  body.     (ISee  p.  o93.) 

t  Meynert  (Strieker's  "Histology,"  Eng.  Trans.,  ii.  p.  456)  calls 
attention  to  the  fact  that  as  the  Cerebral  Hemispheres  increase  in 
size,  so  do  the  motor  divisions  of  the  Crus,  and  so  also  do  the 
Middle  Peduncles  and  'lateral  lobes'  of  the  Cerebellum.  (See 
p.  278  for  some  remarks  touching  this  kind  of  correlation.) 

;j:  From  the  cells  of  the  Corpus  Striatum,  according  to  Meynert, 
there  descend  "  two  subsequently  diverging  tracts,  one  running 
into  the  Spinal  Cord,  the  other  into  the  Cerebellum."  The  latter 
ascends  as  a  thick  fasciculus  in  the  Middle  Peduncle  (loc.  cit.  p. 
875).     This  fasciculus  may  contain  ascending  ('  afferent ')  cerebellar 


508  THE    FUNCTIONAL    RELATIONS    OF    THE 

As  these  'efferent'  fibres  of  the  Cerebellnm  proceed  to  the 
opposite  motor  tracts  of  the  Cerebrum — above  their  seat  of  'deciis- 
satioD  '  in  the  Medulla — the  half  of  the  Cerebellum  whence  they 
issue  would  (by  reason  of  this  lower  'decussation  '  of  the  Anterior 
Pyramids)  be  brought  into  relation  with  the  limbs  of  the  corres- 
ponding side  of  the  body.  This  direct,  rather  than  cross,  relation 
is  also  indicated  by  experimental  observations  with  lower  animals, 
and  by  the  phenomena  of  disease  observable  in  Man. 

Putting  all  these  facts  together,  it  seems  that  the  Cere- 
bellum may  be  regarded  as  an  enormously  developed 
supreme  'motor  centre,'  the  Lateral  Lobes  of  which  co- 
operate in  cross  relation  with  those  of  the  Cerebrum  in 
the  actual  execution  of  Voluntary  Movements ;  though  it 
is  also  an  organ  accustomed  to  act — perhaps  to  a  far 
greater  extent  and  more  continuously — in  the  execution 
of  complicated  Automatic    Movements,    in    response    to 

*  unfelt '  impressions  coming  to  it  (mainly  through  inter- 
nuncial  fibres)  from  '  sensory  nuclei '  of  all  kinds. 

Though  the  Upper  and  Lower  Peduncles  would  seem 
to  be  the  principal  channels  through  which  these  latter 
afferent  impressions  reach  the  Cerebellum,  only  a  part 
of  their  related  outgoing  stimuli  may  go  along  the  Lower 
Peduncles;  others  of  them  may,  in  higher  animals, 
traverse  the  Middle  Peduncles.  However  this  may  be,  it 
would  appear  that  all  afferent  Cerebellar  impressions  that 
are  destined  to  excite  Automatic  Movements,  and  which 
happen  to  emanate  from  one  half  of  the  body,  proceed  to 
the  corresponding  half  of  the  Cerebellum — whether  they 
go  direct  (as  seems  to  be  the  case  with  fibres  from  tho 
Fifth,  the  Auditory  and  other  cranial  nerves),  or  only  after 
two  decussations  (as  seems  to  be  the  case  with  fibres  from 

fibres  as  well  as  descending  (' efferent')  fibres,  if  Meynert's  con- 
clusions are  correct ;  though  the  writer's  notion  is  that  some  at 
least  of  the  Cerebral  '  afferent'  fibres  reixh  ifce  Cerebellum  by  tho 

•  upper  peduncles.' 


Chap.  XXIV.J         PRINCIPAL  PARTS  OF  THE  BRAIN«  509 

the  Optic  Nerves,  and  with  the  ordinary  Sensory  Nerves  of 
the  body). 

In  the  relations,  therefore,  of  the  Cerebrum  with  the 
Cerebellum  for  the  execution  of  Voluntary  Movements,  cross 
connections  exist  analogous  to  those  between  the  Cerebral 
Hemispheres  and  the  opposite  halves  of  the  Spinal  Cord. 
Whilst  in  the  part  which  it  plays  as  a  supreme  motor  • 
centre  in  connection  with  the  higher  kinds  of  Automatic 
Movements,  the  Cerebellum  is  again  called  into  activity 
precisely  as  if  it  were  a  very  specialized  segment  of  the 
Spinal  Cord  itself.* 

If  we  are  to  attempt  shortly  to  sum  up  its  functions,  it 
may  be  said  that  the  Cerebellum  is  a  supreme  Motor 
Centre  for  reinforcing  and  for  helping  to  regulate  the 
qualitative  and  quantitative  distrihiition  of  outgoing  cur- 
rents, in  Voluntanj  and  Automatic  Actions  respectively : 
or,  more  briefly  still,  that  it  is  a  supreme  organ  for 
the  reinforcement  and  regulative  distribution  of  out- 
going currents. 

After  what  has  been  already  set  forth,  and  in  face  of  all 
the  difficulties  previously  enumerated,  it  is  easy  to  imagine 
that  the  Cerebellum  might  appear  to  some  to  be  an 
organ  largely  concerned  with  the  '  co-ordination  of  move- 
ments';  that  it  might  be  regarded  by  others  as  the  seat  of 
a  '  muscular  sense  ' ;  and  that  it  should  seem  to  others 
still,  to  have  to  do  with  the  '  supply  or  liberation  of  motor 
force  for  movements  generally.'  On  the  other  hand,  that 
it  should  appear  to  have  nothing   to  do  with  Instinct, 

*  See  p.  502.  Many  of  these  '  sensori-motor '  or  Automatic  Move- 
ments would,  however,  be  of  a  bilateral  type;  and  such  Movements 
would  probably  be  excitable  through  either  half  of  the  Cerebellum 
(as  it  is  with  the  Cerebrum).  Hence  we  have  another  reason  why 
unilateral  diseases  of  the  Cerebellum  should  often  be  associated  with 
obscure  and  ill-defined  motor  defects. 


510   THE  FUNCTIONAL  RELATIONS  OF  THE  BRAIN 

with  Intelligence,  or  with  Conscious  Sensibility,  notwith- 
standing the  fact  that  it  is  a  recipient  of  fibres  from  all 
kinds  of  *  sensory '  nuclei  is  as  much  in  harmony  with 
reason  as  with  experiment — in  view  of  the  reflex  functions 
which  have  been  assigned  to  it.  And  if  the  function  of 
the  Cerebellum  be  merely  to  discharge  or  give  off  mole- 
cular energy  for  the  initiation  of  Muscular  Movements,  in 
response  either  to  definitely  localized  Volitional  Incitations 
coming  to  it  from  the  Cerebral  Hemispheres,  or  in  response 
to  equally  well  localized  though  '  unconscious  *  Impres- 
sions, coming  from  the  most  various  ^  sensory  '  nuclei  at 
the  base  of  the  Brain  and  in  the  Spinal  Cord ;  we  might 
expect  that  its  microscopic  structure  would  be  practically 
the  same  throughout  all  parts  of  its  vastly  convoluted  and 
extended  superficial  Grey  Matter — and  this  it  is  found 
to  be ;  we  might  expect  also  that  in  so  far  as  it  is  related 
to  the  Cerebral  Hemispheres,  the  Cerebellum  would  act 
only  in  response  to  their  incitations — which  also  seems  to 
be  the  case.  The  view  here  put  forward  seems,  therefore, 
to  be  in  harmony  with  a  great  body  of  known  facts,  and 
to  be  also  capable  of  including  under  it  a  number  of 
opinions  in  regard  to  the  functions  of  this  organ  which 
have  from  time  to  time  been  enunciated,  and  which  have, 
perhaps,  been  faulty  only  by  reason  of  their  more  or  less 
narrow  and  exclusive  nature. 


CHAPTER  XXV. 


phkenology:  old  and  new. 


The  stages  by  which  we  have  arrived  at  what  knowledge 
we  possess  as  to  the  Structure  and  Functions  of  the  Brain 
have  been  very  gradual.  Only  within  the  last  century, 
indeed,  has  the  great  bulk  of  our  present  knowledge  in 
regard  to  it  gradually  taken  shape  from  amidst  the  clouds 
of  error  with  which  the  opinions  of  the  ancients  and  the 
mere  speculations  of  many  of  the  anatomists  of  later  cen- 
turies had  enshrouded  it. 

A  few  particulars  in  regard  to  these  earlier  notions  may 
here  be  given,  which  have  been  culled  and  condensed, 
for  the  most  part,  from  the  writings  of  Prochaska.* 

According  to  Aristotle,  the  heart  was  the  seat  of  the  '  rational 
soul,'  and  the  nerves  (of  whose  relation  to  sensation  and  motion 
he  was  not  ignorant)  arose  therefrom.  The  Brain  was  described  by 
him  as  an  inert  viscus,  cold  and  bloodless,  and  scarcely  to  be  enu- 
merated amongst  the  other  organs  of  the  body — seeing  that  it  was 
of  no  use  except  to  cool  the  heart. 

Erasistratus,  the  grandson  of  Aristotle,  renounced  the  views 
which  he  had  been  taught  by  the  great  master.  He  and  Hero- 
philus  (about  300  B.C.)  were  probably  the  first  to  dissect  tlie 
Human  Brain.  He  originally  said  that  the  sensory  nerves  arose 
from  the  meninges,  or  membranes  of  the  brain,  and  the  motor  from 
the  cerebrum,  though  much  later  in  life  he  modified  this  doctrine 
and  declared  that  both  classes  of  nerves  arose  from  the  medullary 

*  "  Dissertation  on  the  Functions  of  the  Nervous  System." 
(Sydenham  Society's  Translation,  1851 .) 


5V2  PHRENOLOGY:    OLD    AND    NEW. 

matter  of  the  brain;  also  that  the  'animal  spirits'  proceeded  from 
the  brain,  and  the  'vital  spirits'  from  the  heart.  He  recognized 
that  the  Convolutions  were  most  developed  in  the  Brain  of  Man, 
and  attached  importance  to  them  in  relation  to  his  superior  In- 
telligence. 

Galen  (about  a.d.  150)  set  himself  to  refute  the  doctrine  of 
Aristotle.  He  showed  that  the  brain  of  animals  was  hot  instead  of 
cold,  and  that  it  was  well  supplied  with  blood.  He  further  main- 
tained that  its  elaborate  structure  was  against  Aristotle's  notion  of 
its  being  a  mere  refrigerator,  since  for  this  purpose  a  "  rude  and 
formless  sponge,*'  would  have  sufficed.  He  pointed  out  that  the 
brain  was  of  the  same  substance  as  the  nerves,  but  softer,  "  as  it 
necessarily  should  be,  inasmuch  as  it  receives  all  the  sensations, 
perceives  all  the  imaginations,  and  then  has  to  comprehend  all  the 
objects  of  the  understanding,  for  what  is  soft  is  more  easily  changed 
than  what  is  hard."  Since  double  nerves  are  necessary,  the  soft 
for  sensation,  the  hard  for  motion,  so  also  is  the  brain  double,  the 
anterior  being  the  softer,  the  posterior  being  the  harder.  The 
superior  or  '  lateral  ventricles,'  were,  according  to  Galen,  endowed 
with  the  highest  functions.  They  received  air  through  the  nostrils  (by 
way  of  the  ethmoidal  bone  and  the  '  corpora  mammilara  ')  mixing 
this  with  the  *  vital  spirits '  brought  from  the  heart  into  the  ven- 
tricles by  means  of  the  arteries,  and  therefrom  elaborating  the 
•  animal  spirits  '  which  were  thence  transmitted  from  the  brain  to 
the  nerves  for  the  purposes  of  motion  and  sensation.  The  lateral 
ventricles  were  also  held  to  receive  by  the  same  entrance  '  sensible 
objects,'  and  odoriferous  particles.  Galen  likewise  taught  that  the 
brain  had  a  double  movement,  a  diastolic  for  the  reception  of  air  and 
'vital  spirits',  and  a  systolic, by  means  of  which  the  ventricles  distri- 
bute the  '  animal  spirits '  to  the  nerves.  Later  he  held  that  the 
animal  spirits  were  not  contained  in  the  ventricles  only,  but  were 
diffused  throughout  the  whole  substance  of  the  cerebrum  and  the 
cerebellum.  "  The  use  of  the  fornix,  to  which  also  the  corpus  cal- 
losum  belongs,  is  the  same,"  he  says,  "  as  of  the  arches  of  buildings ; 
namely,  to  support  commodiously  and  safely  the  whole  of  the  super- 
jacent part  of  the  brain."  The  corpora  quadrigemina  perform  the 
functions  of  a  janitor,  since  they  serve  to  open  or  shut  the  passage 
by  which  the  '  animal  spirits '  are  transmitted  from  the  anterior  to 
the  posterior  ventricle  through  the  Sylvian  aqueduct. 

Some  centuries  afterwards,  according  to  Prochaska  :  "  The  Arabs 
distributed  the  animal  functions   amongst  the  ventricles  of  the 


Chap.  XXV.]  PHRENOLOGY:    OLD    AND    NEW..  613 

brain,  so  that  one  of  the  anterior  ventricles  they  made  the  seat  of 
common  sensation,  the  other  of"  the  imaginative  faculty,  the  third 
ventricle  was  the  seat  of  the  understanding,  and  the  fourth  of 
memory."  This  doctrine  was  also  maintained  by  Duns  Scotus, 
Thomas  Aquinas,  and  other  theologians.  And  as  late  as  the  first  half 
of  the  seventeenth  century,  "  Descartes  maintained  that  the  animal 
spirits  were  secreted  from  the  brain  through  pores  opening  into  the 
ventricles,  and  that  there  accumulating,  the  slightest  disturbance 
of  them  excites  the  soul  seated  in  the  pineal  gland ;  and  contrarily, 
that  the  animal  spirits  in  the  ventricles  are  moved  by  the  will 
acting  through  the  pineal  gland,  and  distributed  thence  through 
the  nerves  to  all  parts  of  the  body*." 

But  about  the  end  of  the  sixteenth  and  the  beginning  of  the 
seventeenth  century,  Casper  Bauhin,  Yarolius,  Spigelius  and  other 
anatomists,  had  been  striving  to  show,  in  opposition  to  Galen,  that 
the  ventricles  of  the  brain  are  not  the  factories  and  storehouses 
of  the  'animal  spirits,'  and  that  they  are  more  properly  to  I'C 
regarded  as  "  accidental  structures  which  have  no  other  use  than  to 
receive  the  excreta  and  residuum  formed  during  the  nutrition  of 
the  brain,  and  in  the  production  of  the  animal  spirits,  and  to  pass 
them  away  through  the  infundibulum  to  the  fauces." 

After  it  had  been  fully  agreed  that  the  '  animal  spirits '  are  not 
generated  in  the  ventricles  of  the  brain,  nor  produced  in  the 
substance  of  the  brain  to  be  collected  in  the  ventricles,  it  was  still 
generally  believed  that  these  cavities  were  receptacles  for  effete 
matters,  which  discharged  themselves  principally  into  the  nostrils 
through  the  ethmoid  bone  and  through  certain  imaginary  ducts 
indicated  by  Galen,  and  much  later  by  Vesalius,  as  passing  from  the 
pituitary  gland  and  through  the  sphenoid  bone  to  the  fauces. 
This  view  had,  therefore,  in  its  turn,  to  be  overthrown,  and  0.  V. 
Schneider  (1655)  did  much  in  this  direction.  Lower,  Willis,  and 
others,  also  became  convinced  that  nothing  could  pass  from  the 
ventricles  to  the  nostrils  in  the  way  specified;  they  thought,  never- 
theless, "  that  the  serum  of  the  ventricles  passed  through  the  infun- 
dibulum to  the  pituitary  gland,  and  thence  through  peculiar  ducts 
to  the  jugular  veins,  where  it  was  mixed  with  the  blood."     Haller 

*  Even  towards  the  end  of  the  last  century,  a  celebrated  anato- 
mist, Sommering,  announced  his  belief  that  the  fluid  of  the  ven- 
tricles of  the  brain  was  the  real  sensorvmn  commune  and  proper 
organ  of  Mind. 


514  .        PHRENOLOGY:    OLD    AND    NFW. 

admitted  that  the  infundibulum  was  hollow,  but  d'^nied  the  exist- 
ence  of  the  last  mentioned  ducts,  and  maintained  that  the  venlricks 
required  no  special  outlet  for  the  evacuation  of  serum. 

In  regard  to  the  mode  of  generation  of  the  *  animal  spirits  '  it 
was  contended  by  Malpighi,  Willis  (1664)  and  others,  that  they  are 
secreted  in  the  cortical  substance  of  the  brain,  and  thence  received 
into  the  white  or  medullary  substance,  whence  they  are  distributed 
through  the  nerves  to  the  whole  body.  "  The  faculties  of  the  mind, 
such  as  perception,  imagination,  understanding,  and  memory,  were 
banished  from  the  ventricles  together  with  the  animal  spirits,  and 
were  located  by  some  in  the  solid  mass  of  the  brain  ;  by  others 
were  affirmed  to  be  properties  of  the  immaterial  and  rational  soul 
alone,  and  in  no  wise  dependent  on  the  body."  Malpighi  con- 
sidered the  cortical  substance  of  the  brain  to  be  a  true  glandular 
structure. 

Willis  has  been  styled  the  "father  of  phrenology,"  on  account  of 
the  extent  to  which  he  assigned  to  each  particular  part  of  the  brain 
a  special  influence  on  the  mind.  He  held,  "  that  the  cerebrum 
subserves  the  animal  functions  and  the  voluntary  motions,  the 
cerebellum  the  involuntary;  that  a  perception  of  all  the  sensations 
takes  place  in  the  ascending  fibres  of  the  corpora  striata,  and  that 
through  the  descending,  voluntary  movements  are  excited ;  that 
the  understanding  is  seated  in  the  corpus  callosum,  and  memory 
in  the  convolutions,  which  are  its  storehouses;  that  the  animal 
spirits  are  generated  in  the  cortex  of  the  cerebrum  and  cerebellum 
from  the  arterial  blood ;  that  they  collect  in  the  medulla,  are 
variously  distributed  and  arranged  to  excite  the  animal  actions,  and 
distil  through  the  fornix  as  if  through  a  pelican  ;  that  the  animal 
spirits  secreted  in  the  cerebellum  are  ever  flowing,  equally  and  con- 
tinuously, into  the  nerves  which  regulate  involuntary  movements; 
but  those  of  the  cerebrum,  tumultuously  and  irregularly,  according 
as  the  animal  actions  are  vehemently  performed  or  quiescent.  To 
excite  sensations  the  spirits  flow  along  the  nerves  to  the  brain  .  .  . 
As  to  the  loops  of  nerves  with  which  the  arteries  here  and  there 
are  encircled,  he  states  their  use  to  be  to  relax  or  close  the  arteries, 
and  thus  during  various  emotions  of  the  mind  to  admit  the  blood 
in  greater  or  le.ss  quantity  to  certain  parts.  He  decided  that  the 
l)ineal  body  is  not  the  seat  of  the  soul,  but  a  lymphatic  gland." 

The  successors  of  Willis  adopted  some  of  his  doctrines  but  refuted 
others.  Much  bootless  discussion  was  carried  on  by  Boerhave  and 
others  as  to  the  essential   nature  of  the  animal  spirits,  and  in  the 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  515 

early  part  of  the  eighteenth  century  the  following  views  were  also 
expressed  as  to  the  uses  of  certain  portions  of  the  brain.  Yieussens 
I'laced  the  seat  of  imagination  in  the  centrum  ovale ;  Lancisi  and 
Peyronie  maintained  that  all  sensation  is  felt  and  motion  excited 
in  the  corpus  callosum.  Meyer  placed  the  seat  of  memory  in  the 
cortical  matter,  sensation  at  the  origin  of  the  nerves,  and  abstract 
ideas  in  the  cerebellum ;  many,  however,  acknowledged  that  it  was 
not  possible  to  determine  the  seat  of  the  mental  faculties  with  any 
accuracy,  although  there  could  be  no  doubt  that  nature  had  not 
formed  so  many  and  so  various  divisions  of  the  cerebrum  and 
cerebellum  without  an  object. 

Now  came  another  crisis  in  the  history  of  opinions  concerning 
the  brain  and  its  functions.  In  jjreceding  times  the  notion  of  the 
existence  of  'animal  spirits'  was  received  in  an  unquestioning 
manner;  there  had  been  much  discussion  as  to  their  mode  of 
origin,  as  to  their  principal  seat,  and  as  to  their  essential  nature; 
but  these  problems  were  at  last  set  aside  for  one  which  ought  to 
have  preceded  them.  What  evidence  was  forthcoming  as  to  their 
very  existence?  The  supposition  that  what  had  been  termed 
*  animal  spirits '  existed  at  all  now  seemed  to  many  a  gratuitous 
assumption.  After  much  discussion  amongst  the  Stahlians  and 
their  opponents,  we  find  Boerhave,  Haller  (1766)  and  Tissot  acting 
as  the  last  champions  of  the  doctrine  and  striving  to  establish  it 
as  a  truth.  "  Notwithstanding,"  says  Prochaska,  '*  the  authority 
of  these  great  names,  the  love  of  truth  excited  distinguished 
men,  who  advanced  doubts  as  to  this  hypothesis  of  the  animal 
spirits,  and  who  showed  that  the  arguments  adduced  in  its 
favour  proved  nothing  when  carefully  analysed,  an(^that  the 
whole  h^'pothesis  was  altogether  devoid  of  truth."  Writing,  there- 
fore, in  1784,  Prochaska  says  :  "  We  will  term  the  cause  latent  in 
the  pulp  of  the  nerves,  producing  its  effect  and  not,  as  yet  ascer- 
tained, the  vis  nervosa ;  we  will  arrange  its  observed  effects,  which 
are  the  functions  of  the  nervous  system,  and  discover  its  laws." 

The  same  writer  considered  it "  by  no  means  improbable  that  each 
division  of  the  intellect  has  its  allotted  organ  in  the  brain,"  though 
as  he  himself  frankly  admitted,  nothing  definite  could  at  that  time 
be  said  on  the  subject.  "  Hitherto,  it  has  not  been  possible,"  he 
adas,  "  to  determine  what  portions  of  the  cerebrum  or  the  cerebellum 
are  specially  subservient  to  this  or  that  faculty  of  the  mind.  The 
conjectures  by  which  eminent  men  have  attempted  to  determine 
these  are  extremely  improbable,  and  that  department  of  physiology 


616  PHRENOLOGY:    OLD    AND    NEW. 

is  as  obscure  now  as  ever  it  was."  It  must  not  be  forgotten,  how- 
ever, that  it  was  Prochaska  himself  who  first  fully  described  the 
nature  of  '  reflex  movements.'  "  The  sensorium  commune,''^  he 
says  (loc.  cit.  p.  446),  "  reflects  the  sensorial  impressions  into  motor 
by  definite  laws  peculiar  to  itself,  and  independently  of  conscious- 
ness." Prochaska,  moreover,  recognized  that  the  same  kind  of 
process  might  take  place  in  the  systemic  ganglia,  since  he  says 
(p.  438) :  "  It  seems  probable,  therefore,  that  besides  the  sensorium 
commune,  which  we  conjecture  to  be  in  the  medulla  ohlongata, 
'medulla  spinalis,  pons  Varolii,  and.  crura  of  the  cerebrum  and 
cerebellum,  there  are  special  sensoria  in  the  ganglia  and  plexuses 
of  the  nerves,  in  which  external  impressions  ascending  along  the 
nerves  are  reflected,  that  need  not  ascend  all  the  way  to  the  senso- 
rium commune,  to  be  reflected  thence." 

The  space  available  in  this  work  does  not  permit  of  an 
attempt  to  trace,  even  in  hare  outline,  the  successive  steps 
hy  which  during  the  last  hundred  years  we  have  been 
slowly  tending  to  acquire  a  more  exact  (though  still  wholly 
inadequate)  knowledge  of  the  Functions  of  different  parts 
of  the  Brain.  Something  of  this  sort  may,  however,  be 
gathered  from  the  work  of  Vulpian*  on  the  "  Physiology  of 
the  Nervous  System,"  and  from  other  sources.  What  has 
here  been  already  said  will  indicate  how  much  required 
to  be  done  ;  and  what  is  about  to  he  said  will  give  some 
faint  noUon  as  to  the  present  paucity  of  real  knowledge, 
and  as  To  the  need  in  which  we  stand  of  much  further 
light  in  many  directions. 

Having  considered  the  relations  of  the  Cerebral  Hemi- 
spheres with  one  another,  with  the  Cerebellum,  and  with 
the  halves  of  the  body,  the  reader's  attention  must  now 
be  limited  to  the  Hemispheres  themselves,  in  order  that  he 
may  learn,  in  this  and  in  the  next  chapter,  something  of 
what  has  been  made  out  concerning  the  parts  of  these  all- 
important  organs  which  appear  to  be  more  especially  con- 
*  "  Lecons  sur  la  physiologic  du  systeme  uerveux,"  1866. 


CuAP.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  517 

cerned  with  Perceptions,  Volitions,  and  other  Mental 
Processes. 

Again,  we  shall  have  to  rely  upon  the  same  three  classes 
of  facts  as  constituted  the  hasis  for  our  conclusions  in  the 
previous  chapter,  though  they  will  not  be  appealed  to  in 
quite  the  same  relative  proportions.* 

The  notion  that  the  Brain  is  the  principal  organ  of  Mind, 
and  that  there  is  a  localization  of  function  in  its  several 
parts,  was,  as  we  have  seen,  a  fundamental  position  fi  Ily 
realized  by  Prochaska  and  others,  long  before  Gall  and 
Spurzheim  (1805-1826)  began  zealously  to  study  the  ana- 
tomy of  the  organ  and  to  promulgate  in  connection  there- 
with a  '  Physiognomical  System '  which  soon  attracted 
great  attention  under  the  name  of  *  Phrenology.'  Its 
authors  were  enthusiasts  who  attempted  to  systematize  an 
extremely  complex  subject  prematurely,  when  knowledge 
in  regard  to  it  was  altogether  in  its  infancy — and  that, 
too,  without  professing  to  have  much  special  knowledge  or 
ability  for  the  carrying  out  of  at  least  one  half  of  the  work 
involved  in  such  an  enterprise. 

Gall  and  Spurzheim  were  well  abreast  of,  and  even 
leaders  of  the  knowledge  of  their  day  in  regard  to  the 
anatomy  of  the  Brain,  yet  at  the  time  they  elaborated  their 
doctrines  notbing  was  known  to  them,  any  more  than  to 
their  predecessors,  as  to  the  real  physiological  distinction 
existing  between  the  'grey'  and  the  'white'  substance  of  the 
Cerebrum.  They,  like  those  who  had  gone  before  them, 
regarded  the  white  matter  of  the  hemispheres  as  the  essen- 
tial nervous  substance,  while  the  Grey  Matter  was  con- 
sidered to  be  "  the  matrix  of  the  nervous  fibres" — a  forma- 
tive material,  in  fact,  which,  wherever  it  was  found,  served 
only  as  a  nucleus  for  the  adequate  production  of  nerve 
fibres. t     The    Grey    Matter  of  the  Convolutions,  there- 

*  See  p  477.     f  See  Spurzlieim's  "  Anatomy  of  the  Brain,"  p.  7. 
23 


518  PHRENOLOGY  :    OLD    AND    NEW. 

fore, — the  matter  which  we  now  helieve  to  be  so  largely 
concerned  with  the  most  delicate  and  subtle  of  Brain- 
functions — was  by  the  founders  of  Phrenology  considered 
to  have  no  proper  nerve  functions  at  all. 

No  attempt,  indeed,  was  made  to  take  any  account  of 
more  than  about  one  half  of  it.  Their  analysis  of  the 
Human  Mind  was  supposed  to  have  been  complete. 
The  various  Faculties,  Emotions,  and  Propensities  were 
assigned  to  their  respective  seats,  corresponding  externally 
with  the  upper  and  outer  parts  of  the  skull.  But  the  Con- 
volutions of  the  base  of   the  Brain,  those  resting  on  the 

*  tentorium  Cerebelli,'  and  those  of  the  contiguous  inner 
faces  of  the  Hemispheres,  were  credited  with  no  share  of 
mental  functions.  The  use  of  this  convolutional  Grey 
Matter  being  altogether  differently  estimated  by  the 
Phrenologists  from  what  it  is  at  present,  their  '  System  ' 
was  devised  and  their  organology  defined  with  no  special 
reference  thereto.  Incredible  as  this  may  seem  to  many 
persons  at  the  present  day,  it  is  strictly  true.  The 
haphazard  constitution  and  boundaries  of  their  so-called 

*  organs '  may  indeed  be  learned  from  the  words  of 
Spurzheim  himself.  "  The  organs,"  he  says,*  *'are  not 
confined  to  the  surface  of  the  brain :  they  extend  from 
the  surface  to  the  great  swelling  of  the  occipital  hole 
(medulla  oblongata)  and  probably  include  even  the  com- 
missures ;  for  the  whole  mass  of  the  brain  constitutes  Iho 
organs." 

It  need  scarcely  be  said,  at  the  present  day,  that  no 
such  divisions  of  the  Brain  as  are  here  indicated,  either 
internally  or  externally,  have  any  real  existence  ;  and  if  the 
convoluted  surface  of  the  organ  itself  presents  no  such 
divisions  as  are  to  be  seen  on  a  phrenological  cast,  by 
which  the  several  supposed  *  organs '  could  be  marked  off 
*  "  The  Physiognomical  System,"  1815,  p.  239. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  519 

from  one  another,  it  needs  little  anatomical  knowledge  to 
imagine  how  much  more  impossible  it  must  be  to  divine 
such  boundaries  through  the  skull  and  its  integuments. 
If  we  take  the  organ  of  'philoprogenitiveness,'  for  instance, 
whose  assigned  situation  at  the  back  of  the  head  may  be 
seen  in  any  phrenological  bust,  we  find  that  it  corresponds 
with  a  bony  prominence,  which  varies  greatly  in  thickness 
in  different  individuals,  whilst  internally  it  corresponds  to 
the  point  of  union  of  four  great  venous  sinuses,  and  within 
these  as  much  to  the  tips  of  the  Occipital  Lobes  as  to  a 
part  of  the  upper  and  posterior  border  of  the  Cerebellum.* 

The  division  of  the  human  Mind  into  distinct  *  facul- 
ties,' after  the  fashion  of  the  phrenologists,  is,  however, 
an  error  in  itself,  quite  apart  from  the  unsatisfactory 
nature  of  theh-  particular  analysis.  "  Every  form  of  ia- 
telhgence  being,"  as  Herbert  Spencer  says,f  "in  essence 
an  adjustment  of  inner  to  outer  relations,  it  results  that, 
as  in  the  advance  of  this  adjustment  the  outer  relations 
increase  in  number,  in  complexity,  in  heterogeneity,  by 
degrees  that  cannot  be  marked,  there  can  be  no  valid 
demarcations  between  the  successive  phases  of  intelli- 
gence ....  fundamentally  considered,  intelligence 
has  neither  distinct  grades  nor  is  constituted  of  faculties 
that  are  truly  independent  ....  its  highest  phe- 
nomena are  the  effects  of  a  complication  that  has  arisen 
by  insensible  steps  out  of  the  simplest  elements." 

This  philosophical  view  of  Herbert  Spencer  is  one 
which  is  quite  harmonious  with  what  we  know  of  the 
progressive  development  of  the  Brain  in  the  animal  series. 

But  the  crudity  of  the  psychological  analysis  of  the 
Phrenologists  is  well  capped  by  the  simplicity  of  the  mode 
in  which  they  proceeded  to  assign  the  sites  of  the  seve- 
ral '  organs.'  Spurzheim  says  : — ''  Two  persons  at  V'ienna 
*  See  figs.  147,  118.     \  "  Principles  of  Psychology,"  1st  Ed.  d.  486. 


520  PHRENOLOGY  :    OLD    AND    NEW. 

were  known  to  be  remarkable  for  their  extreme  irresolu- 
tion ;  and  therefore  one  day  in  a  public  place  Gall  stood 
behind  them  and  observed  their  heads.  He  found  them 
extremely  large  on  the  upper  and  posterior  part  of  both 
sides  of  the  head ;  and  this  observation  gave  the  first  idea 
of  this  organ."  Such  was  the  kind  of  haphazard  tentative 
method  by  which,  after  multitudinous  observations  con- 
ducted, it  is  true,  upon  persons  of  all  kinds,  ages,  and 
stations  in  society,  the  details  of  their  '  System '  were 
finally  established. 

The  '  system  of  Phrenology  '  of  Gal]  and  Spurzheim  was, 
therefore,  fallacious  in  almost  every  respect.  It  was  alto- 
gether defective  in  its  psychological  analysis,  eminently 
unsatisfactory  in  its  localizations,  and  was,  in  short,  as  un- 
reliable in  its  methods  as  it  was  inconclusive  in  its  results. 
It  would  have  been  almost  needless,  indeed,  to  have  dwelt 
so  long  upon  this  subject  but  for  the  fact  that  amongst 
the  general  public  there  are  probably  very  many  who,  if 
not  actual  believers  in  the  '  Phrenology '  of  Gall  and 
Spurzheim,  may  be  glad  to  know  upon  what  precise 
grounds  the  system  should  be  rejected. 

Are  we,  however,  to  run  into  the  opposite  extreme,  and 
subscribe  to  such  doctrines  as  those  put  forth  by  Flourens 
(1840)  ?  This  eminent  physiologist,  who  may  be  said  almost 
to  have  been  the  initiator  of  experimental  research  as 
directed  to  the  determination  of  the  Functions  of  the  Brain, 
felt  entitled  to  draw  from  his  own  well-known  investi- 
gations the  following  conclusions,  altogether  opposed  to 
any  localization  of  functions  in  detail — that  is,  of  special 
functions  in  special  regions  of  the  Cerebral  Hemispheres. 
His  conclusions  are  these  ("  Eech.  Experiment.,"  p.  99): — ■ 

"  Ainsi  1°,  on  pent  retrancher,  soit  par  devant,  soit  par  derricro, 
soit  par  en  haiit,  suit  par  cote,  line  portion  assez  etendue  des  lobes 
cerebraux,  sans  que  leurs  fonctioas  soient  perducs.     Una  vortion 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  5'21 

assez  restrainte  de  ces  lohes  sujffit  do7ic  a  Vexercice  de  leura  fonc- 
tio7is." 

"2°.  A  mesure  que  ce  retrancheraent  s'opere,  toutes  les  fonctiona 
s'affaiblissent  et  s'eteigneiit  graduellement;  et  passe  certames 
limites,  elles  sont  tout-a-fait  eteintes.  Les  lohes  cerebraux  con- 
courent  done  par  tout  leur  ensemble  a  Vexercice  plein  et  entier  de 
leurs  fonctions. 

"3°.  Enfin,  des  qu'une  perception  est  perdue  toutes  le  sont;  dea 
qu'une  faculte  disparait,  toutes  disparaissent.  II  n'y  a  done  point 
de  sieges  divers  ni  pour  les  diverses  facultes,  ni  pour  les  diver ses 
perceptions.  La  faculte  de  percevoir,  de  juger,  de  vouloir  une  chose 
reside  dans  le  merae  lieu  que  celle  d'en  percevoir,  d'en  juger,  d'en 
vonloir  une  autre ;  et  consequemment  cette  faculte,  essentiellement 
une,  reside  essentiellement  dans  une  seule  organe." 

But,  notwithstanding  the  fact  that  these  early  and 
difficult  experimental  investigations  seemed,  as  Flourens 
thought,  to  entitle  him  to  draw  some  such  conclusions,  his 
views  could  not  claim  a  ready  assent.  T  If  we  are  to  regard 
Ihe  Brain  as  the  principal  organ  of  Mind,  and  to  look  upon 
each  mental  operation  as  one  of  the  manifestations  of  its 
functional  activity,  all  analogy  and  even  probability  would 
point  to  the  conclusion  that  a  definite  order  must  be 
observed,  and  that  identical  mental  operations  will  always 
be  associated  with  the  functional  activity  of  identical  tracts 
of  nerve  fibres  and  cells  in  the  Brain  and  its  dependencies. 
We  know  that  the  Olfactory,  the  Optic,  and  the  Auditory 
Nerves,  each  go  to  different  parts  of  the  Brain,  so  that  the 
primary  processes  in  relation  with  the  exercise  of  the  cor- 
responding Senses  are  distinct  from  one  another.  Can  we 
believe  that  in  their  later  or  higher  phases  the  tracts  fcr 
such  impressions  lose  their  distinctness  ?  Again,  I  touch  the 
table  at  which  I  am  now  writing,  with  my  forefinger :  the 
impression  thus  produced  travels  by  means  of  nerve  fibrer 
along  a  perfectly  definite  route  from  the  part  touched  to 
my  Spinal  Cord.  Can  I  doubt  that  the  route  by  which  it 
reaches  the  Brain  is  just  as  definite  (though  not  so  well 


522  PHRENOLOGY  :    OLD    AND    NEW. 

known),  and  that  a  similar  impression  would  always  fol- 
low the  same  route,  so  long  as  the  conducting  channels 
remained  uninjured  ?/ In  some  such  sense  as  this  'locali- 
zation' would  seem  to  be  a  simple  a  priori  necessity.  But 
if  it  holds  good  for  Sensorial  Operations  it  will  be  equally 
likely  to  obtain  for  Intellectual  Operations  and  Emotions. 
Order  and  regularity  could  scarcely  be  absent  in  the 
carrying  on  of  the  functions  of  those  parts  of  the  Brain 
alone,  where,  from  the  subtle  nature  and  multiplicity  of 
the  molecular  actions  involved  in  myriads  of  cells  and 
fibres,  these  particular  characteristics  of  lower  Brain-actions 
would  scv  m  to  be  so  preeminently  needful. 

The  fundamental  question  of  the  existence,  or  not,  of 
real  'localizations'  of  function  (after  some  fashion)  in  the 
Brain  must  be  kept  altogether  apart  from  another  secondary 
question,  which,  though  usually  not  so  much  attended  to, 
is  no  less  real  and  worthy  of  our  separate  attention.  It 
is  this  :  Whether,  in  the  event  of  '  localization '  being 
a  reality,  the  several  Mental  Operations  or  Faculties  are 
dependent  {a)  upon  separate  areas  of  Brain- substance,  or 
(b)  whether  the  'localization'  is  one  characterized  by  mere 
distinctness  of  cells  and  fibres  which,  however,  so  far  as 
position  is  concerned,  may  be  interblended  with  others 
having  different  functions.  Have  we,  in  fact,  to  do  with 
topographically  separate  areas  of  Brain-tissue  or  merely 
with  distinct  cell  and  fibre  mechanisms  existing  in  a  more 
or  less  diffuse  and  mutually  interblended  manner? 

The  latter  kind  of  arrangement  seems,  on  the  Avhole,  to 
be  an  even  more  probable  one  than  the  former,  and  may 
commend  itself  most  to  many  persons.  The  existence 
of  some  such  arrangement  won  Id  help  to  throw  light 
upon  some  of  the  results  obtained  by  Flourens,  and, 
indeed,    upon  doctrines  advocated  by  Brown- Sequard  at 


CfiAP.  X5V.]  PHRENOLOGY  :    OLD    AND    NEW.  623 

tlie  present  day.  It  makes  it  possible  to  recognize  a  cer- 
tain amount  of  truth  in  them,  without  thereby  involving 
us  in  a  denial  of  the  all-important  principle  of  *  locali- 
zation,' as  applied  to  cells  and  fibres. 

Brown- Sequard  has  indeed  of  late  *  expressed  himself 
most  positively  in  favour  of  the  diffuse  and  interblended 
arrangement.  He  thinks  he  can  prove,  beyond  question, 
that — "  motor  or  other  centres,  as  commonly  conceived, 
that  is  to  say,  as  agglomerations  of  cells,  having  one 
and  the  same  function,  and  which  form  a  more  or  less 
definitely  limited  mass,  do  not  exist."  The  existence  of 
the  other  mode  of  arrangement  would  equally  with  the 
latter  make  it  necessary  to  admit  that  cells  having  the 
same  kind  of  functional  activity  should  be  in  communi- 
cation with  one  another  by  means  of  processes.  And,  as 
he  contends,  the  functional  activity  of  similar  cells  might, 
in  either  case,  be  conjointly  and  equally  well  carried  on 
through  the  intervention  of  intercellular  processes.  It 
w^ould,  in  fact,  make  comparatively  little  difference 
whether  such  similar  cells  were  closely  packed  together  or 
whether  they  were  scattered  over  comparatively  wide  areas 
of  the  Cerebral  Cortex.  So  far,  at  least,  the  writer  finds 
himself  thoroughly  in  accord  with  Brown- Sequard. 

Thus,  whilst  a  topographically  separate  localization  of 
independent  '  faculties  '  seems  to  the  writer  altogether  im- 
probable,! he  fully  believes  that  certain  portions  of  the 
Cerebral  Hemispheres — the  Anterior  Lobes  for  instance — 
are  always  concerned  in  the  carrying  on  of  Intellectual 
and  Volitional  Operations  of  practically  the  same  nature, 
though  of  different  degrees  of  complexity  in  different 
individuals.  Yet  it  can  scarcely  be  said  of  "  carrying 
on,"  but  rather  of  assisting  and  aiding  to  carry  on,  cer- 

*  "  Archiv.  de  Physiol,  norm,  et  path.,"  2nd  Ser.  IV.  p.  412. 
t  See  "  Journal  of  Mental  Science,"  January,  1869. 


521  PHRENOLOGY:    OLD    AND   NEW. 

tain  Intellectual  and  Volitional  Operations  ;  for  it  seems 
improbable  that  even  such  a  lai-ge  division  of  a  Cerebral 
Hemisphere  as  the  Anterior  Lobe  has  a  distinct  set  of 
functions  peculiar  to  itself.  The  division  into  '  lobes '  is, 
in  the  main,  an  entirely  artificial  one,  and  the  grey  matter 
of  the  anterior  region  is,  as  we  have  seen,  intimately 
related  to  the  grey  matter  of  the  middle  and  posterior 
parts  of  the  Hemispheres;  so  that,  just  as  our  psychical 
nature  consists  of  one  great  complicated  but  unbroken 
network  in  which  are  bound  together  Sensations,  Percep- 
tions, Judgments,  Emotions,  and  Volitions,  so  is  the 
physical  organ  corresponding  to  these  also  represented  by 
the  most  complicated  and  intricate  network  of  nerve-cells 
and  nerve-fibres,  mutually  bound  together  and  brought 
into  functional  relation  with  one  another.  Whilst,  there- 
fore, it  may  truly  be  said  that  the  Anterior  Lobes  are 
always  concerned  in  the  carrying  on  of  Intellectual  and 
Volitional  Operations  of  the  same  nature,  they  may  be 
mainly  instrumental  in  some  functions,  and  they  may  take 
part,  to  a  minor  degree,  in  the  execution  of  certain  other 
Mental  Operations  depending  more  especially  upon  the 
functional  activity  of  different  parts — the  Parietal,  the  Tem- 
poral, or  the  Occipital  Lobes,  singly  or  in  combination. 

Perception,  Intellect,  Emotion,  and  Volition  are  so 
intimately  associated  with  one  another  in  our  ordinary 
mental  processes  that,  if  we  were  even  to  attempt  a  defi- 
nite mapping  out  of  their  territories,  so  as  to  allot  a 
separate  province  in  the  Cerebral  Hemispheres  for  each  of 
these  great  divisions  of  Mind,  we  should  probably  fall  into 
a  grievous  error.  In  precisely  those  parts  of  the  Cerebral 
Hemispheres  that  are  most  concerned  when  we  look  upon 
a  fine  painting  or  a  fine  piece  of  statuary,  may  we  imagine 
the  emotions  of  admiration  kindled,  to  which  the  sight 
of  these  objects  of  art  has  given  rise — however  much  the 


Chap.  XXV.]  PHRENOLOGY:    OLD    AND    NEW.  525 

activity  of  other  centres  may  co-operate ;  and  just  as  the 
sight  of  ripe  fruit  upon  a  tree  may  incite  a  *  desire  '  to 
possess,  followed  by  a  Volitional  Stimulus  for  the  purpose 
of  obtaining  the  desired  object ;  so  in  this  case  the  parts 
concerned  in  the  manifestation  of  the  '  desire,'  and  those  in 
which  the  Volitional  Stimulus  originates,  are  probably 
situated  within  some  portions  of  that  same  area  of  con- 
volutional  grey  macter  which  was  concerned  in  the  Percep- 
tive Act  itself. 

On  the  other  hand,  as  the  writer  has  elsewhere  said,* 
**  inasmuch  as  we  have  certain  distinct  avenues  of  know- 
ledge (throoigh  the  Sense  Organs  and  their  proximate 
nerve  ganglia),  and  the  Cerebral  Hemispheres  are  the  parts 
concerned  in  the  elaboration  of  impressions  so  derived,  we 
can  well  understand  that  the  impressions  entering  through 
one  gate  or  sense-avenue,  may  pass  through  the  substance 
and  towards  the  periphery  of  these  Cerebral  Hemispheres 
in  certain  definite  directions,  and  according  to  accustomed 
routes.  Then,  the  impressions  entering  through  another 
gate  of  knowledge,  or  avenue  of  sense,  may,  and  probably 
do,  pursue  a  different  direction  through  its  substance,  so 
that  at  the  periphery  the  fibres  and  cells  concerned  in  the 
conduction  and  elaboration  of  these  impressions  may 
exist  in  maximum  quantity  in  different  portion?  of  the 
surface  of  the  Hemispheres — though  in  part  they  may 
occupy  jointly  the  same  area,  and  be  intertwined  with  the 
fibres  and  cells  concerned  in  the  elaboration  of  the  pre- 
viously mentioned  set  of  impressions.  And  so  on  with 
the  various  sense  organs  and  their  ultimate  expansions  in 
the  form  of  what  I  would  call  '  Perceptive  Centres '  in  the 
Cerebral  Hemispheres.  Thus,  though  there  may  be  much 
and  compound  overlapping  of  areas,  and  though  the  area 
pertaining  to  the  impressions  of  any  particular  sense  in 
*  *'  Journal  of  Mental  Science,"  January,  1869. 


526  PHRENOLOGY  :    OLD    AND    NEW. 

the  Cerebral  Hemispheres  may  be  a  very  extended  one  (not 
to  speak  of  the  still  further  complication  brought  about 
by  the  communication  established  between  the  nerve  cells 
of  one  sense  area  with  those  of  others  in  the  same  Hemi- 
sphere, and  of  the  probable  union  by  means  of  commis- 
sural fibres  between  analogous  parts  of  the  two  Hemi- 
spheres), still  it  may  w^ell  be  that  certain  portions  of  the 
surface  of  the  Cerebral  Hemispheres  might  correspond 
more  especially  to  the  maximum  amount  of  nerve  cells 
and  fibres  pertaining  to  some  one  or  other  of  the  various 
senses.  .  .  .  Just  as  certain  of  the  senses  contribute 
in  a  preponderating  degree  towards  the  buildii^*  up  of  our 
mental  impressions  and  their  corresponding  volitional 
results  (e.g.,  those  of  Sight,  Hearing,  and  Touch),  so  we 
may  imagine  that  these  sense  organs  would  be  connected 
internally  with  a  comparatively  wide  area  of  cortical  sub- 
stance in  each  Hemisphere.*  It  would  be  fair  to  infer  as  a 
probability,  therefore,  that  the  '  perceptive  centres '  for 
visual  impressions,  and  also  those  for  acoustic  impres- 
sions, w^ould  have  a  wide-spread  seat  in  the  cerebral  hemi- 
spheres, whilst  those  pertaining  to  the  gustatory  and 
olftictory  senses  would  have  a  more  limited  distribu- 
tion." 

With  merely  a  few  verbal  alterations  the  views  above 
stated  were  put  forth  by  the  writer  in  papers  written  in 
1865  and  1869.  And  simple  as  the  notion  may  now  seem 
that  we  have  a  right  to  look  for  distinct '  Perceptive  Centres' 
in  the  cortical  substance  of  the  Hemispheres,  which  should 
be  in  direct  "structural  relation  with  their  respective  sen- 
sory nerves  and  lower  ganglia  (or  *  nuclei '),  in  or  near 
the  Medulla — no  mention  of  this  kind  of  '  localization  '  was 
up  to  that  period  to  be  found  in  medical  or  physiological 

*  A  notion  of  this  kind  lias  lately  been  supported  also  by  Prof. 
Croom  Robertson  in  "Mind,"  1877,  p.  97- 


Chap.  XXV.]  PHRENOI.OGY:    OLD    AND    NEW.  527 

works;*  although,  as  the  writer  then  first  attempted  to 
show,  SQch  notions  threw  much  light  upon  Cerebral 
Physiology,  and  upon  certain  defects  of  Speech  resulting 
from  disease  of  the  Brain. f  The  writer's  views  were  shortly 
afterwards  endorsed  and  extended  by  Dr.  Broadbent,  in 
a  valuable  paper  on  the  "  Cerebral  Mechanism  of  Speech 
and  Thought."  } 

Soon,  moreover,  physiologists  began  in  earnest  to 
search  for  such  *  Perceptive  Centres '  in  the  cortical 
grey  matter.  The  first  to  do  this  was  Dr.  Ferrier, 
though  he  makes  no  reference  to  the  writer's  views.  He 
took  up  the  enquiry,  perhaps  independently — certainly 
in  a  thoroughly  systematic  manner — and  his  results 
deserve  to  be  most  carefully  studied.  §  The  notion 
that  there  ought  to  be  such  '  perceptive  centres '  evi- 
dently commended  itself  to  Ferrier,  and,  with  charac- 
teristic energy,  he  sought  to  throw  light  upon  their  locali- 
zation, as  he  had  previously — instigated  by  the  views  of 
Hughlings    Jackson — sought  to  establish    the    existence 

*  No  such  conclusions  were  to  be  inferred,  from  the  views 
concerning  Cerebral  Physiology  put  forward  in  this  country 
generally.  There  is  a  philosophical  opposition,  in  fact,  between 
them  and  doctrines  which  have  been  widely  promulgated  by  Dr. 
Carpenter  (see  an  article  on  "  Sensation  and  Perception, '  "Nature," 
Dec.  23,  1869,  and  Jan.  20,  1870,  p.  309). 

t  See  "  Physiology  of  Thinking  "  ("  Fortnightly  Review,"  Jan- 
uary, 1869),  and  "  Defects  of  Speech  in  Brain  Disease  "  (•'  Brit,  and 
For.  Med.  Chir.  Rev.,"  January  and  April,  1869). 

+  "  Med.  Chir.  Trans.,"  1872,  p.  180.  Writing,  indeed,  in  the 
**  Journal  of  Mental  Science  "  for  April,  1870  (p.  23),  Broadbent 
says  : — '*  These  convolutions  then  which  rdceive  central  fibres,  and 
are  bilaterally  associated  by  the  C.  callosum,  will  constitute  the 
perceptive  centres  of  Dr.  Bastian." 

§  His  first  communication  on  this  subject  was  presented  to  the 
Eoyal  Society,  in  April,  1875,  and  is  to  be  found  in  Pt.  IL  of 
that  year's  "  Phil.  Trans.,"  p.  415. 


523  PHRENOLOGY:    OLD    AND    NEW. 

of  distinct  '  motor  centres '  in  the  cortex  of  the  Cerebral 
Hemispheres. 

Till  quite  recently  there  has  been  a  notable  dearth  of 
evidence  in  medical  literature  in  regard  to  the  existence 
and  localization  of  any  such  '  Perceptive  Centres ' — either 
in  man  or  in  the  lower  animals.  We  have,  as  already 
explained,  good  reason  for  believing  that  sensory  or 
*  ingoing'  fibres  from  the  body  generally  pass  to  the 
Cerebral  Hemispheres  in  the  upper  or  posterior  layers  of 
the  Cerebral  Peduncles  ;  and  that  in  the  situation  where 
each  of  these  expands  within  its  own  Hemisphere  into 
the  so-called  *  corona  radlata  '  such  ingoing  fibres  corres- 
pond to  the  posterior  third  of  this  fan -like  expansion, 
and  are  there  joined  by  fibres  coming  from  the  lower 
ganglia  or  'nuclei'  in  relation  with  the  organs  of 
Sight,  Hearing  and  Taste.  Destruction  of  this  portion  of 
the  peduncular  fibres  is  found  to  cut  off  all  sensory 
impressions  —  special  as  well  as  general  —  proceeding 
from  -the  opposite  half  of  the  body  (p.  490).  But,  whilst 
our  knowledge  is  good  to  this  extent,  we  are  still  much 
in  the  dark  as  to  the  relations  of  these  sensory  fibres 
with  the  Thalamus  (and,  indeed,  as  to  the  precise  func- 
tions of  this  body  generally),  as  well  as  concerning  the 
ultimate  distribution  of  the  several  sets  of  fibres  to 
particular  regions  of  the  cerebral  cortex — where  alone 
their  respective  impressions  seem  to  culminate  and  be- 
come associated  with  subjective  phenomena,  or  States  of 
Consciousness. 

The  fact  of  this  absence  of  evidence  in  regard  to  the  sitnation  of 
the  '  Perceptive  Centres '  of  Man  seems  at  first  very  surprising, 
since  it  might  be  imagined  that  a  study  of  the  multitudinous 
records  of  local  disease  implicating  the  surface  of  the  Brain  which 
exist  in  medical  works  would  soon  settle  the  problem.  This,  how- 
ever, is  far  from  being  the  case,  and  that  for  many  reasons  which 
need  not  now  be  detailed.     Suffice  it  to  say,  that  local  le&ions  of 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  529 

the  mere  cortex  of  one  Cerebral  Hemisphere  in  man  have  apparently 
never  been  known  to  be  definitely  associated  with  loss  of  Smell, 
of  Sight,  or  of  Hearing  on  either  side  of  the  body."*^  This  peculiar 
circumstance  seems  to  be  specially  related,  as  the  writer  pointed  out 
in  1874,f  to  the  duplicate  nature  of  the  Brain,  and  to  the  fact  of 
the  connection  of  each  of  its  Hemispheres  with  the  double  and 
intimately  united  lower  ganglia  or  nuclei  of  each  of  the  Special 
Senses. 

In  consequence  of  such  an  anatomical  arrangement  one  Hemi- 
sphere seems  often,  in  a  very  short  time  after  the  occurrence  of 
damage  or  injury  to  its  fellow,  to  be  capable  of  being  brought 
into  relation  with  sensory  impressions  from  both  sides  of  the 
body,  so  that  although  the  'perceptive  centre'  for  the  sense  of 
Sight,  of  Smell  or  of  Hearing,  may  be  destroyed  in  the  convolu- 
tions of  one  hemisphere,  no  blindness  of  the  opposite  eye  or  no 
unilateral  loss  of  smell  or  hearing,  as  the  caue  may  be,  is  produced. 
It  is  quite  possible  that,  in  the  first  instance,  there  may  b(! 
some  unilateral  loss  or  weakness  of  one  or  other  of  the  special 
Senses  when  one  of  its  convolutional  centres  is  damaged,  although 
this  defect,  in  the  early  days  of  an  illness,  may  easily  pass  un- 
observed. Failure  of  observation  in  regard  to  such  points  as 
these,  is  a  matter  of  very  common  occurrence  at  the  commencement 
of  an  acute  disease  of  the  Brain,  both  on  the  part  of  a  patient 
and  of  his  medical  attendant.  Such  defects  would,  very  probably, 
not  be  noticed  or  ascertained  unless  they  were  specially  looked  for, 
as  Ferrier  has  of  late  rightly  enough  maintained.  Still  the  extreme 
rarity  of  unilateral  impairments  of  Smell,  Sight,  or  Hearing,  as 
immediate  effects,  in  association  with  diseases  or  injuries  of  one 
hemisphere  of  the  Brain  stands  out,  as  a  very  notable  fact,  in 
regard  to  which  all  the  best  observers  are  unanimous. 

If  light  is  to  be  thrown,  therefore,  upon  this  very 
interesting  question  within  any  brief  period,  recourse 
must  be  had  to  experiments  with  some  of  the  lower 
animals.  Of  these.  Monkeys  are  obviously  the  most 
suitable  of  all,  on   account   of  the  general   resemblance 

*  An  approximation  to  this  knowledge  had,  however,  been 
arrived  at  in  regard  to  Smell.  For  reference  to  cases,  see  Ferrier's 
"  Functions  of  the  Brain,"  p.  191. 

t  "Lancet,"  July  25,  1874,  p.  111. 


530  PHRENOLOGY:    OLD    AND    NEW. 

which  ohtains  between  the  Brain  of  these  animals  and 
that  of  Man.  Such  experiments  have  been  made  with 
much  skill  and  judgment  by  Dr.  Terrier,*  to  whose 
writings  the  reader  must  be  referred  for  full  details  as 
to  his  numerous  observations,  and  the  validity  of  the  tests 
adopted.  Here  there  is  space  only  for  a  brief  enunciation 
of  the  results  and  conclusions  at  which  he  has  arrived. 


TSL 

Fig.  172.— Left  Hemi^^phere  of  the  Brain  of  a  Monkey  (Macacu.'<\  A,  fissure 
of  Sylvius  ;  B,  fissure  of  Rolando  ;  C,  Parieto-occipital,  or,  perpendicular  fissure  ; 
F  L,  Frontal  Lobe ;  P  L,  Parietal  Lobe  ;  O  L,  Occipital  Lobe ;  T  S  L,  Temporal  Lobe ; 
F,  upper,  F2,  middle,  F3,  lower  Frontal  Convolution;  sf,  supero-frontal  Sulcus; 
if,  infero-frontal  Sulcus  ;  ap,  antero-parietal  Sulcus  ;  AF,  xVscending  Frontal,  and  AP, 
Ascending  Parietal  Convolution  ;  P  P  L,  Postero-Parietal  Lobule ;  A  G,  Angular 
gyrus;  i]^,  intra-parietal  Sulcus;  T,  T2,  T3,  Upper,  Middle,  and  Lower  Temporal 
Convolutions  ;  ti.  <2, Upper  and  Lower  Temporal  Sulci;  Oi,  O2,  O3,  Upper,  Middle,  and 
Lower  Occipital  Convolutions  ;  01,  02,  first  and  second  Occipital  Fissures.     (Ferrier.) 

These  experiments  of  Ferrier  are  supposed  by  him  to 
support  the  notion  that'  perceptive  centres  '  limited  in  area, 
and  topographically  distinct  from  one  another,  exist  in  the 
cortex  of  the  Cerebral  Hemispheres.  His  facts,  however, 
do  not  necessarily  carry  with  them  any  such  interpretation. 
They   are  quite  capable  of  being  explained  in  accordance 

*  See  "  Philos.  Trans.  1875,"  Pt.  II.,  and  ''  The  Functions  of  the 
Brain,"  1877,  chap.  ix. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  531 

with  what  we  hold  to  he  the  more  probable  theory,  viz.: 
that  such  '  perceptive  centres  '  or  mechanisms  are  diffuse 
in  seat  and  interblended  with  others.  This,  indeed,  has 
been  pointed  out  by  Prof.  Croom  Eobertson,*  who  says  : — 
**  so  there  is  no  intrinsic  improbability — rather  the  reverse 
— in  the  view,  that  impressions  received  by  any  organ  of 
sense  are  all  carried  up  first  to  a  particular  region  of  the 
cortical  substance  before  they  are  brought  into  relation 
with  other  impressions  and  with  motor  impulses,  or  are 
otherwise  elaborated  in  the  brain.  It  may  w^ell  be  that 
there  are  special  sensory  regions  in  the  brain-cortex,  and 
that  Dr.  Ferrier  has  given  the  first  rough  indication  of 
their  locality."  Each  set  of  sensory  fibres  might,  in  fact, 
direct  themselves  towards  some  particular  part  of  the 
cerebral  cortex,  whence  the  fibres  might  diffuse  themselves 
more  or  less  widely.  These  '  first  cortical  stations,'  or 
regions  from  which  sensory  fibres  diffuse  themselves  in 
different  directions,  may  have  no  real  claim  to  be  considered 
as  '  centres,'  and  yet  the  same  kind  of  results  may  follow 
from  their  destruction  or  stimulation  as  if  they  were  real 
*  centres.'!  And  owing  to  the  subsequent  diffusion  of  the 
several  kinds  of  fibres,  other  regions  are  not  likely  to  be 
revealed  by  experimental  investigation  which  w^ould  have 
any  similar  claims  to  be  regarded  as  *  sensory  centres.' 
Croom  Robertson  truly  says,  sensations  themselves  "can 
neither  be    supposed   to    be  consummated  at  their  first 


*  Sere  a  review  of  Dr.  Ferrier's  work  in  "  Mind,'  1877,  pp.  96,  97. 

t  C.  Eobertson  aptly  remarks,  "Peripheral  impressions  may  be 
utterly  prevented  from  coming  into  consciousness  by  the  cortical 
lesion ;  but  it  does  not  follow  that  the  last  act  of  the  nervous 
process  involved  in  a  conscious  sensation  of  touch  is  naturally 
consummated  there  and  nowhere  else  in  the  brain,  or  that  in  all 
that  region  there  is  no  work  done  but  such  as  (objectively)  we  call 
touch." 


532 


PHRENOLOGY:    OLD    AND    NEW. 


eortical  station,  nor  be  either  traced  or  thought  likely  to 
be  traced  farther  by  any  experimental  means  yet  devised." 
Although  Ferrier's  determination  of  the  sites  which  are 
of  most  importance  for  each  Sense  require  more  confirma- 
tion by  other  workers  than  they  have  yet  received,  before 
they  can  be  finally  accepted  as  correct,  the  discrimination 
and  ability  with  wdiich  his  experiments  have  been  con- 
ducted should  ensure  for  them  that  careful  and  thorough 
testing  which  their  importance  deserves. 


Q/7t9 


Foy 


Fig.  173.— Internal  Aspect  of  the  Right  Hemisphere  of  a  Monkey  {Macacus).  CO, 
Corpus Callosvim  divided ;  C,  internal parieto-occipital  Fissure;  Cm  s,  Calloso-marginal 
Fissure;  Cf,  Calcarine  Fissure;  c?/,  Dentate  Fissure;  Cs,  Collateral  Fisure;  G  F, 
Gyrus  fomicatus ;  CM,  Marginal  Convolution ;  0  U,  Uncinate  Convolution ;  S, 
Crochet,  or  subiculum  cornu  Aramonis ;  Q,  Quadrilateral  Lobule ;  Z,  Cuneus  ; 
FO,  Orbital  Lobule.     (Ferrier.) 


Well  conducted  experiments  upon  animals  are  pecu- 
liarly needed  and  suitable  for  throwing  light  upon  this 
obscure  problem  as  to  the  possible  localization  of  ^perceptive 
centres'  in  the  Hemispheres,  because  when  numerous 
trials,  as  to  the  effects  of  local  stimulation  or  destruction 
of  different  regions  of  the  Hemisphere,  may  have  enabled 
the  experimenter  to  fix  upon  some  portion  of  the  cortex  as 
the  main   seat  of  one  of  such  centres,  it  is  then  in  his 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  533 

power  at  will  to  call  into  existence  conditions  which 
almost  never  exist  in  the  case  of  disease  in  the  human 
subject — that  is,  he  can  produce  symmetrical  destructions 
in  corresponding  regions  of  the  two  Hemispheres,  and 
knowing  that  such  lesions  alone  exist,  can  thereafter  most 
carefully  test  the  animal's  condition  in  respect  of  the 
sense- endowment  supposed  to  be  interfered  with. 

Taking  first  of  all  the  case  of  the  sense  of  Sight,  we  find 
Ferrier  localizing  its  '  perceptive  centre  '  in  the  '  angular 
gyrus '  and  part  of  the  '  supra-marginal  lobule  '  (fig.  174). 


Fia.  174. — Brain  of  Monkey,  showing  sliaded  area  corresponding  with  so-called 
Visual  Centre  in  the  cortex  of  left  Csrebral  Hemisphere.     (Ferrier.) 

Destruction  of  such  parts  on  one  side  in  an  animal  rendered 
insensible  by  chloroform,  seemed  to  produce  blindness 
of  the  opposite  eye  for  a  day  or  more — judging  from  the 
effects  of  bandaging  the  other  eye  for  a  time  and  then 
removing  the  bandage,  so  as  to  be  able  to  watch  and 
contrast  the  animal's  behaviour  under  these  different  con- 
ditions. After  a  day  or  two,  the  animal  experimented 
upon  again  appeared  to  see  with  both  eyes.  Where, 
however,  these  regions  of  the  cortex  had  been  destroyed  in 
both  Hemispheres,  the   creature   became   blind   in   both 


534  PHRENOLOGY :    OLD    AND    NEW 

eyes,  and  did  not  subsequently  recover  from  this  condi- 
tion. Instead  of  a  temporary  defect  on  the  side  opposed 
to  the  unilateral  lesion,  the  animal's  sight  was  now  per- 
manently lost  on  both  sides.* 

After  comparative  observations  upon  the  effects  of  uni- 
lateral and  double  destructive  lesions,  Ferrier  localized  the 
*  perceptive  centre '  for  the  sense  of  Hearing  in  the  upper 
half  of  the   'superior  temporal  convolution'  (fig.   175). 


Fig.  175.  —Brain  of  Moukey,  slaowing  a  shaded  area  corresponding  with  the  so- 
called  '  Auditory  Centre '  in  the  Cortex  of  the  right  Cerebral  Hemisphere.    (Ferrier.) 

Here  again  destruction  of  this  region  in  one  Hemisphere 
was  found  to  lead  only  to  a  very  temporary  deafness  in 
the  ear  of  the  opposite  side  of  the  body ;  whilst  destruc- 
tion of  the  same  region  in  both  Hemispheres  caused  a 
lasting  and  total   deafness   on  both   sides.     Eeferring  to 

*  See  p.  393  for  the  notification  that  in  the  brain  of  Prof.  De 
Morgan  there  was  no  appreciable  difference  in  the  appearance  of  the 
'  angular  gyrus  '  aud  the  '  supra-marginal  lobule  '  on  the  two  sides 
of  the  brain,  although  this  celebrated  mathematician  had  been  blind 
on  one  side  almost  from  birth.  In  the  examination  of  the  Brain  of 
a  deaf  and  dumb  woman,  moreover,  Broadbent  ("Jrnl.  of  Anat.  and 
Physiol.,"  vol.  iv.  p.  218)  neither  records  the  existence  of  nor  repre- 
sents any  special  atrophy  in  the  '  sui3erior  temporal  convolutions. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  535 

one  of  the  animals  on  which  he  studied  these  effects, 
Ferrier  says  :^" 

"The  angular  gyrus  had  just  been  cauterized  on  the  left  side, 
with  the  effect  of  causing  blindness  in  the  right  eye  alone,  and 
without  any  affection  of  hearing  or  the  other  senses.  The  su^Dcrior 
temporo-sphenoidal  convolution  was  then  exposed  and  cauterized 
on  both  sides,  the  lesion,  as  was  ascertained  jpost-mortem,  being 
confined  to  this  region.  After  complete  recovery  from  the  opera- 
tion, the  various  senses  and  powers  of  voluntary  motion  were  tested 
repeatedly.  Touch,  taste,  and  smell  were  perfect;  and  sight,  as 
indicated  by  the  animal's  perfect  freedom  of  movement  and  ability 
to  find  its  food  and  drink,  practically  -unimpaired  twenty-four  hours 
after  the  operation.  As  regards  hearing  it  was  difficult  to  devise 
a  satisfactory  test  owing  to  the  alertness  of  the  animal,  and  the 
attention  that  it  gave  to  everything  around  it.  A  loud  sound  close 
beside  it  caused  a  start,  which,  however,  could  not  be  taken  as  a 

test  of  hearing  proper  as  distinguished  from  reflex  action sf 

In  order  to  avoid  attracting  its  attention  by  sight,  I  retired  behind 
the  dcor  and  watched  the  animal  through  a  chink,  while  it  sat 
comfortably  before  the  fire.  When  all  was  still  I  called  loudly, 
whistled,  knocked,  &c.,  without  attracting  the  animal's  attention 
to  the  source  of  the  sound,  though  it  was  sitting  perfectly  awake 
and  looking  around.  On  my  cautiously  approaching  it,  it  remained 
unaware  of  my  proximity,  until  I  came  within  the  field  of  vision, 
when  it  started  suddenly  and  made  grimaces  as  if  in  terror  or  alarm. 
On  repeating  these  tests  when  the  monkey  was  sitting  quietly 
along  vAth.  a  companion  monkey  whose  powers  of  hearing  were  un- 
questionable, the  companion  invariably  became  startled  at  the 
sounds,  and  came  peering  curiously  to  ascertain  their  origin,  while 
the  other  remained  quite  still.'* 

In  regard  to  the  seat  of  the  *  perceptive  centre '  for  the 
sense  of  Smell  we  have  anatomical  indications  of  great 
value.     The  connection  of  the  '  olfactory  tract,'  with  the 

*  *'  Functions  of  the  Brain,"  p.  174. 

f  These  startings  produced  by  near  noises  are,  as  Ferrier  very 
justly  says,  "  to  be  regarded  as  reflex  phenomena  of  the  same 
nature  as  those  observed  by  Flourens,  in  the  case  of  pigeons 
deprived  of  their  hemispheres,  wheu  a  pistol  was  fired  close  to  the 
head." 


536  PHRENOLOGY:    OLD    AND    NEW. 

tip  of  the  Temporal  Lobe  (or,  indeed,  the  actual  continuity 
which  exists  between  these  parts  in  many  animals),  as 
Ferrier  says,  "might  of  itself  be  regarded  as  establishing 
strong  grounds  for  a  physiological  connection  between  this 
region  and  the  sense  of  smell."  He  adds  :  "  In  the  monkey 
and  in  man  the  direct  connection  between  the  outer  root 
of  the  comparatively  small  olfactory  tract  and  the 
subiculum  *  is  not  so  evident,  though  in  the  monkey  it 
is  more  apparent  than  in  man.  The  origin  of  this  so- 
called  root  from  the  subiculum  is,  however,  thoroughly 
established  by  microscopical  investigation." 

A  lesion  of  one  subiculum  was  found  to  cause  diminu- 
tion or  abolition  of  Smell  on  one  side,  viz.,  the  side  of 
lesion — thus  confirming  the  direct  relation  above  indicated. 
For,  as  Ferrier  points  out,f  "  Neither  the  inner  roots  which 
fuse  with  the  gyrus  fornicatus  on  each  side,  nor  the  outer 
roots  which  are  connected  with  the  subicula,  and  thence 
through  the  posterior  pillars  of  the  fornix  with  the  optic 
thalami,  undergo  decussation,  and  hence  there  is  no 
anatomical  basis  of  cross  connection  between  the  olfactory 
bulbs  and  their  cerebral  centres."  Destruction  of  both 
these  regions,  was  found  to  cause  loss  of  Smell  on  both 
sides,  of  a  permanent  character. } 

*  This  name  is  given  to  the  inner  part  of  the  tip  of  the  Tempo- 
ral Lobe,  or  more  precisely  to  the  tip  of  the  *  uncinate  convolution,' 

t  Loc.  cit.  p.  185. 

X  An  attempt  to  explain  the  lack  of  decussation  of  the  olfactory 
channels  has  been  hazarded  on  p.  482.  The  sense  of  Smell  (the 
organs  of  which  are  situated  on  each  side  of  the  middle  line  of  the 
body)  is  just  that  mode  of  sensibility  in  which  no  discrimination  is 
ever  made  between  the  impressions  coming  from  the  two  sides.  No 
sort  of  disturbance  or  embarrassment  would  therefore  seem  likely 
to  be  produced  from  the  fact  that  impressions  of  smell  from  the 
right  nostril,  are  brought  into  relation  in  the  corresponding  Cere- 
bral Hemisphere  with  gustatory,  visual,  auditory,  and  tactile  im- 
pressions emanating  from  the  left  side  of  the  body,  and  vice  versa. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  5B7 

Owing  to  the  protected  position  of  the  tip  of  the 
Temporal  Lobe,  accurate  limitation  of  lesions  in  this  situa- 
tion was  found  to  be  almost  impossible.  Hence,  though 
the  '  centre  '  for  Taste  is  believed  by  Ferrier  to  be  imme- 
diately contiguous  with  that  for  Smell,  viz.,  in  "  the  lower 
part  of  the  middle  temporo-sphenoidal  convolution,"  at 
the  tip  of  the  Temporal  Lobe,  he  is  unable  to  speak 
with  so  much  certainty  as  to  this  localization.  "  The 
abolition    of    taste,"    he    says,    *' always   coincided   with 


FiQ.  176.— Brain  of  Monkey,  showing  shaded  area  in  Temporal  Lobe,  the  destruc- 
tion of  which  caused  loss  of  Smell  on  the  same  side,  and  loss  of  Taste  on  the 
opijosite  side.     (Ferrier.) 

destruction  of  regions  situated  in  close  relation  to  the 
subiculum  ;  "  whilst  in  favour  of  the  part  above  defined 
being  the  centre  for  Taste,  he  remarks  that  irritation  of 
this  portion  of  the  '  middle  temporal  convolution '  leads  to 
movements  of  the  lips,  tongue,  and  cheek  pouches,  which 
he  regards  as  "  reflex  movements  consequent  on  the  ex- 
citation of  the  gustatory  sensation."  Destruction  of  this 
region  on  one  side  produced  temporary  loss  or  impair- 
ment of  Taste  on  the  opposite  side  of  the  tongue ;  whilst 
the  loss  of  this  sense  became  complete,  double,  and  per- 


533  PHRENOLOGY:    OLD    AND    NEW. 

manent,  when  the  same  part  was  destroyed  on  both 
sides.* 

Destruction  of  the  whole  of  the  tip  of  one  Temporal 
Lobe,  was  found  to  produce  a  temporary  loss  of  Smell  on 
the  same  side  and  loss  of  Taste  on  the  opposite  side. 

In  regard  to  the  seat  of  the  '  centre  '  for  Tactile  and 
Common  Sensibility,  some  difficulty  was  at  first  experi- 
enced in  fixing  upon  any  site  which  seemed  especially 
concerned  with  such  impressions.  Ferrier  saj^s  :  "After 
numerous  experiments,  in  which  almost  the  whole  outer 
surface  of  the  hemisphere  had  been  successively  destroyed 
without  causing  loss  of  the  sense  of  touch,  it  seemed  to 
me  strange  if  such  an  important  intellectual  sense  should 
not,  like  the  others,  have  a  special  centre  in  the  hemi- 
sphere. My  attention  was,  therefore,  directed  to  the  inner 
aspect  of  the  temporo-sphenoidal  lobe,  and  to  devise  a 
method  by  which  this  region  might  be  reached  and 
destroycl ."  Ferrier  soon  succeeded  in  getting  at  this  region 
from  behind,  and  his  subsequent  experiments  induced  him 
to  regard  the  *  hippocampus  major  '  and  the  overlying 
'uncinate  convolution '  as  the  parts  which  are  specially  to  be 
regarded  as  the  centre  for  Tactile  Impressions  (fig.  177). 
Destruction  of  this  region  causes  complete  loss  of  sensibility 
in  the  opposite  half  of  the  body,  and  that,  too,  of  a  more 
permanent  character  than  the  diminution  which  occurs  in 
other  modes  of  sensibility  from  unilateral  destruction  of 
their  convolutional  '  centres  ' — a  result  which  is  so  far  in 
exact  accordance  with  what  may  be  frequently  recognized 
as  the  effect  of  disease  of  the  Brain  in  Man.-j- 

*  Ferrier  says  :  *'  With  the  abolition  of  taste,  cutaneous  sensibility 
of  the  tongue  was  also  abolished,  a  fact  inelicating  the  association 
in  the  hemisphere  of  the  centres  of  tactile  and  special  sensation  in 
the  tongue."     (Log.  cit.  p.  180.) 

t  "  Paralysis  from  Brain  Disease,'  1875,  pp.  109,  121. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  539 

As  regards  the  establishment  of  the  existence  or  absence 
of  Tactile  Sensibility  in  an  animal  under  observation,  the 
same  kind  of  difficulty  is  encountered  as  in  regard  to  the 
other  senses,  owing  to  the  uncertainty  besetting  the  dis- 
crimination of  a  mere  reflex  reaction  to  stimulation,  from 
one  which  has  resulted  from  a  conscious  Perception. 
Ferrier  therefore  "  endeavoured  to  apply  such  tests  as 
might  clearly  distinguish  between  the  two  cases,  relying 
more    on    the    evidence    furnished    by   the    spontaneous 


Fig.  177.— Internal  Aspect  of  the  right  Hemisphere  of  the  Brain  of  a  Monkey, 
showing  a  darkly  shaded  area  corresponding  with  the  so-called  '  Tactile  Centre,'  and, 
by  dotted  lines,  the  direction  in  which  an  instrument  was  inserted  for  the  destruc- 
tion of  this  area.   (Ferrier.) 

activity  of  the  animal  than  on  mere  response  to  cutaneous 
stimulation." 

He  operated  upon  a  Monkey  which  was  in  the  main  left- 
handed,  that  is,  one  which  took  things  offered  to  it  pre- 
ferably with  the  left  hand.  "  For  this  reason  the  right 
hippocampal  region  was  destroyed,  with  the  view  of  affect- 
ing the  sense  of  touch  in  the  limb  which  the  animal 
usually  employed."     The  results  are  thus  described.* 

"  After  recovering  from  the  operation  and  the  narcotic  stupor, 
sight  and  hearing  were  found  to  be  unimpaired,  and  the  intelligence 
quick  and  active  as  before.   But  cutaneous  stimulation  by  pricking, 

*  Loc.  cit.  p.  179. 


540  PHRENOLOGY:    OLD    AND    NEW. 

pinching,  or  pungent  heat  sufficient  to  cause  lively  manifestationg 
of  sensation  when  applied  to  the  right  side  of  the  body,  failed  in 
general  to  elicit  any  reaction  whatever  on  the  left  side,  whether 
face,  hand,  or  foot.  Only  occasionally  when  the  stimulus  was 
intense  or  long  continued,  did  reaction  at  all  ensue.  This  most 
remarkable  absence  of  response  of  any  kind  rendered  the  fact  of 
annihilation  of  tactile  sensibility  almost  completely  proved  without 
further  evidence." 

An  alteration  in  the  character  of  the  Movements  capable 
of  being  executed  by  the  left  limbs  also  existed,  which,  as 
Ferrier  thinks,  was  of  the  kind  '^  due  to  the  loss  of  tactile 
sensation  by  which  movements  are  guided."  It  seems 
almost  more  than  doubtful,  however,  in  the  face  of  much 
recent  evidence,  whether  'ataxy'  of  Movement  is  neces- 
sarily or  even  ever  occasioned  by  mere  loss  of  cutaneous 
sensibility  (see  pp.  582,  700). 

But  a  digression  becomes  needful  at  this  point,  on 
account  of  the  complex  nature  of  Tactile  and  Common 
Sensibility,  and  their  relations  to  the  so-called  sixth  or 
*  Muscular  Sense.'  It  is  highly  important  that  definite 
notions  should,  if  possible,  be  arrived  at  in  regard  to 
the  latter  endowment,  in  order  that  we  may  learn  how  far 
anything  w^orthy  of  the  name  exists,  apart  from  the 
various  modes  of  Tactile  and  Common  Sensibility — and 
also,  incidentally,  Avhat  mode  of  sensibility  it  is  by  which 
Movements  are  principally  guided. 

Under  the  head  of  Tactile  and  Common  Sensibility  are 
to  be  included  many  different  kinds  of  Impressions  more 
or  less  distinct  from  one  another.  Thrown  into  a  tabular 
form  they  may  be  thus  arranged : 


/'  1.  Tactile  impressions  proper. 


a.  From      Shin     and  \  2.  Impressions  of  contact  and  pressure. 
Mucous       Mem  -  j  4.  Impressions  of  temperature. 
hranes.  \  3.  Impressions  of  paiu. 


Chap.  XXV.]  PHRENOLOGY:    OLD    AND    NEW.  541 

^  1.  Impressions  (ill   defined)  of  strain  or 
b.  From  Muscles.  <  tension. 

(.  2.  Impressions  of  pain  (rare). 

TT-  -n      '      m       r  !•  Impressions  (ill  defined)   of  strain  or 

€.  ±  roni  Fascue,  Ten-  \  ^  ^  ^ 

J  J  n  "S  pressure. 

do}is,  and  Bones.    J  r,    t  •  /.       •     /        % 

V.  2.  Impressions  oi  pam  (rare). 

r  1.  Impressions    of    contact    or   pressure 
d.  From  Viscera,  ^  (rare). 

C  2.  Impressions  of  pain  (more  common). 

The  different  modes  of  sensibility  botli  in  Skin  and  in 
Mucous  Membranes  are  found  to  vary  in  their  acuteness 
in  certain  diseases  of  the  Cord  or  Brain,  quite  out  of 
relation  to  one  another.  Thus  the  ability  to  discriminate 
between  heat  and  cold,  or  the  sensitivity  to  painful  im- 
pressions may,  either  separately  or  together,  be  abolished 
in  parts  which  are  still  sensitive  to  impressions  of  con- 
tact (tactile  sensibility  or  touch  proper),  or  vice  versa. 
Hence  it  is  that  some  distinguished  physiologists  believe 
these  different  kinds  of  Impressions  to  be  conducted  by 
separate  nerve  fibres  ;  whilst  others,  with  as  much  evidence 
in  favour  of  their  view,  consider  that  the  same  nerve  fibres 
are  capable  of  being  impressed  in  different  modes,  so  as 
to  conduct  different  kinds  of  molecular  vibrations — and 
that  they  may  hence  give  rise  to  Impressions,  whose 
subjective  phases  differ  to  the  extent  above  mentioned. 

Passing  from  considerations  of  this  kind,  we  have  now 
to  face  the  related,  though  much  more  important,  set  of 
questions,  as  to  the  existence,  nature,  and  origin  of  a 
separate  endowment,  commonly  spoken  of  as  the  Muscu- 
lar Sense.  These  questions  have  much  occupied  the 
attention  of  physiologists,  pathologists,  and  psychologists 
— and  especially  the  latter — during  recent  years.  So 
much  importance,  indeed,  is  assigned  to  the  '  Muscular 
24 


542  PHRENOLOGY:    OLD    AND    NEW. 

Sense  *  impressions  by  psychologists  that  it  becomes  above 
all  things  necessary  for  clear  and  comprehensive  notions 
to  be  entertained  as  to  the  real  nature  of  any  such  en- 
dowment. Prof.  Bain,  for  instance,  maintains  that  unless 
certain  views  are  held  in  regard  to  the  muscular  sense — 
unless  it  be  deemed,  as  he  terms  it,  an  '  active  '  mode 
of  sensibility  directly  dependent  VL])on  motor  nerves  and 
motor  centres — *'the  most  vital  distinction  within  the 
sphere  of  mind  is  bereft  of  all  physiological  support."* 
This  may  or  may  not  be  true ;  but  in  any  case  it  shows 
the  importance  of  being  able  to  arrive  at  correct  notions 
concerning  an  endowment  upon  the  nature  of  which  so 
much  of  philosophical  doctrine  is  supposed  to  depend. 
Croom  Eobertson  has  also  of  latef  referred  to  the  sub- 
ject as  "  one  of  the  first  importance  in  the  psychology  of 
the  present  day." 

The  views  expressed  at  different  times  in  regard  to  the 

*  Muscular  Sense,'  and  the  means  by  which  we  appreciate 

*  resistance  '  have  been  so  various  and  contradictory  as  to 
make  it  almost  impossible  to  give  the  student  of  this 
question  any  adequate  notion  of  the  real  problems  requiring 
solution  without  bringing  together  some  historical  notes 
illustrative  of  the  various  opinions  that  have  been  held 
on  the  subject.  Some  of  these  notes  of  earlier  date  were 
originally  supplied  by  Sir  Wm.  Hamilton  ;  but,  as  much 
light  has  recently  been  thrown  upon  the  subject  by  obser- 
vations of  cases  of  Hemi-annosthesia  occurringin  the  human 
subject  it  is  in  all  respects  convenient,  and  even  necessary, 
that  the  whole  question  should  be  reconsidered.  This 
has  been  don* ;  but  as  the  discussion  of  the  question 
constitutes  a  digression  too  lengthy  to  be  introduced  into 
this  chaj^ter,  and  as  it  is  evidently  technical  in  nature,  it 

■  •'  Senses  and  Intellect,"  3id  ed.,  p.  77, 
t  "Mind,"  1377,  p.  98. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  543 

has  been  thouglit  better  to  relegate  it  to  an  Appendix 
(p.  691),  and  here  merely  to  introduce  the  view  which  seems 
best  supported  by  the  evidence  there  adduced,  together 
with  some  suggestions  which  may,  perhaps,  be  calculated 
to  obviate  confusion' in  the  future. 

The  conclusion  there  arrived  at  is  that  the  term 
*  Muscular  Sense  *  ought  to  be  abolished,  as  being  in 
several  respects  misleading,  when  applied  (as  it  often  is) 
with  totally  distinct  significations,  partly  referring  to  some 
and  partly  to  all  the  impressions  which  we  derive  from 
our  moving  members,  or  from  Movements  generally.  We 
may  much  more  reasonably  and  conveniently,  in  the  face 
of  all  the  disagreements  concerning  the  '  muscular  sense,* 
speak  of  a  Sense  of  Movement,*  as  a  separate  endowment, 
of  a  complex  kind,  whereby  we  are  made  acquainted  with 
the  position  and  movements  of  our  limbs,  whereby  we  judge 
of  '  weight '  and  '  resistance,'  and  by  means  of  which  the 
Brain  also  derives  much  unconscious  guidance  in  the  per- 
formance of  Movements  generally,  but  especially  in  those 
of  the  automatic  type.  Impressions  of  various  kinds 
combine  for  the  perfection  of  this  '  sense  of  movement,' 
and  in  part  its  cerebral  seat  or  area  coincides  with  that  of 
the  sense  of  Touch.  There  are  included  under  it,  as  its 
several  components,  cutaneous  im.pressions,  impressions 
from  muscles  and  other  deep  textures  of  the  limbs  (such 
as  fasciae,  tendons,  and  articular  surfaces),  all  of  which 
jield  Conscious  Impressions  of  various  degrees  of  defi- 
niteness ;  and  in  addition  there  seems  to  be  a  highly 
important  set  of  '  unfelt '  Impressions,  which  guide  the 
motor  activity  of  the  Brain  by  automatically  bringing  it 

*  Or  in  one  word,  Kinaestliesis  (from  Kiveco,  to  move  and 
alcrdrjai^,  sensation).  To  speak  of  a  '  Kinassthetic  Centre'  will 
certainly  be  found  more  convenient  than  to  speak  of  a  '  Sense  of 
Movement  Centre.* 


544  PHRENOLOGY:    OLD    AND    NEW. 

into  relation  with  the  different  degrees  of  contraction  of 
all  Muscles  that  may  be  in  a  state  of  action. 

Such  impressions,  in  such  groups,  differ  from  those  of 
all  other  Sense  Endowments  inasmuch  as  they  are  'results' 
rather  than  '  causes  '  of  Movement,  in  the  first  instance ; 
and  are  subsequently  used  only  as  guides  for  promoting 
the  continuance  of  Movements  already  begun  (p.  69).  But 
in  other  cases  the  *  ideal '  revival  of  some  such  impressions 
will  cooperate  with  certain  sensorial  or  'volitional '  stimuli 
for  the  renewal  of  Movements  that  have  been  executed  at 
some  previous  time. 

The  experiments  of  Ferrier  are  thought  by  him  to  show 
that  the  sensibilities  pertaining  to  Muscles,  Fascise,  Ten- 
dons, and  Joints  depend  upon  Impressions  which  diffuse 
themselves  in  and  from  the  same  cortical  area  as  that 
ivhich  is  related  to  the  more  superficial  Cutaneous  luq^res- 
sions.  By  certain  cortical  lesions,  as  well  as  by  lesions  of 
the  posterior  part  of  the  '  internal  capsule,'  all  these  modes 
of  Tactile  and  Common  Sensibility  have  been  thought  to 
be  impaired  or  abolished  together. 

It  is  quite  possible,  however,  to  find  that  in  certain 
diseases  of  the  Spinal  Cord,  the  sensibility  of  the  Skin  may 
be  impaired  or  lost,  whilst  that  of  the  Muscles  and  other 
deeper  structures  is  retained ;  or  in  other  cases  for  the 
sensibility  of  the  Skin  to  be  preserved  whilst  that  of  the 
Muscles  is  lost ;  *  and  in  others  still,  for  ordinary  superficial 
and  deep  sensibility  to  be  preserved,  whilst  the  transit  of  the 
*  unconscious '  impressions  from  Muscles,  above  referred 
to,  is  more  or  less  interfered  with,  so  that  whilst,  in 
such  a  case,  there  is  neither  motor  nor  sensory  paralysis, 
there  may  be  an  inability  to  co-ordinate  Movements  with- 
out the  aid  of  Sight. f 

♦  Jaccoud,  "  Les  paraplegics  et  I'ataxie,"  1804;. 
f  Landry,  "Traite  des  j)aralysios,"  1859. 


CiiAP.  XXV.]  PHTvENOLOGY:    OLD    AND    NEW.  545 

In  regard  to  Visceral  Impressions,  the  reader  must 
now  be  well  aware  that  sensations  are  not  habitually 
received  from  internal  organs,  and  that  vague  impressions 
only  are  felt  at  intervals  so  long  as  these  organs  continue 
in  a  healthy  condition.  That  impressions,  however, 
habitually  pass  from  some  of  the  viscera  to  the  Brain, 
although  devoid  of  conscious  accompaniments,  can  be 
shown  by  good  indirect  evidence.  Systemic  impressions 
are,  in  this  manner,  liable  to  exercise  an  important 
influence  upon  the  genei-al  current  of  our  Thoughts  and 
Emotions,  and  they  may  also  modify  to  a  marked  extent 
the  activity  of  the  Brain  within  the  spheres  of  one  or 
more  of  the  Special  Senses.  Thus,  though  not  themselves 
attended  by  Consciousness,  it  is  unquestionably  true  that 
various  '  visceral  impressions '  powerfully  modify  the  Con- 
scious Life  of  lower  animals  as  well  as  of  Man. 

It  is  more  than  probable,  therefore,  that  these  Systemic 
Impressions  pass  by  definite  routes  through  the  Medulla 
and  lower  parts  of  the  Brain,  and  thence  upwards  to  some 
definite  region  of  the  Cerebral  Cortex,  whence  they  possi- 
bly radiate  in  different  directions.  The  fact  that  the 
impressions  are  of  an  '  unconscious  '  type  need  not  inspire 
doubts  as  to  whether  they  reach  the  Cerebral  Cortex.  The 
probabilities  are  greatly  in  favour  of  their  doing  so. 

The  parts  of  the  Cortex,  hov/ever,  to  which  such  impres- 
sions principally  proceed  is  at  present  unknown.  Ferrier 
is  inclined  to  believe  that  they  go  to  the  Occipital  Lobes. 
But  the  evidence  adduced  by  him  seems  to  the  writer 
inadequate  to  support  such  a  conclusion,  and  he  himself 
does  not  strongly  insist  upon  it.*  Apart,  moreover,  from 
the  dubious  nature  of  the  special  evidence  upon  which 
Ferrier' s  opinion  in  regard  to  the  cerebral  localization 
of  Visceral  Impressions  is  based,  this  conclusion  is  one 
*  "Functions  of  the  Brain,"  p.  192 


546  PHRENOLOGY:    OLD    AND    NEW. 

which  does  not  commend  itself  very  highly  when  judgecl 
by  general  evidence  open  to  all.  It  is  surely  a  little 
repugnant  to  warrantable  inferences  to  be  asked  to  believe 
that  impressions  so  primordial  as  the  '  systemic  '  through- 
out the  Vertebrate  Series  (and  which  would  seem  to 
diminish  rather  than  increase  in  importance  in  the  higher 
members  of  the  series)  should  have  most  to  do  with  one 
of  the  latest  evolved  and  most  specialized  portions  of  the 
Cerebrum.  This  general  evidence,  indeed,  as  the  writer 
has  elsewhere  suggested,  points  rather  to  the  greater  pro- 
portionate implication  of  the  Occipital  Lobes  with  the 
higher  Intellectual  Activity  of  which  the  animal  is 
capable.*  The  latter  notion  has  also  been  supported  by 
Dr.  Hughlings  Jackson  and  others,  because  of  its  accord- 
ance with  many  facts  supplied  by  sufferers  from  diseases 
of  the  Brain. 

It  does  not  at  all  follow  that  Visceral  Impressions  from 
the  two  sides  of  the  body  should,  like  the  majority  of 
sensory  impressions,  decussate  in  some  part  of  their 
course  to  the  Cerebral  Hemispheres.  No  similar  advantage 
would  result  from  the  decussation  of  such  impressions. 
In  the  first  place,  no  uniform  bilateral  symmetry  is  met 
with  throughout  the  Viscera  ;  and  secondly,  if  the  crossing 
of  other  sensory  strands  has  been  brought  about  in  the 
manner  we  have  attempted  to  indicate  (p.  478)  no  object 
would  be  gained  by  a  similar  decussation  of  Visceral  Im- 
pressions. This  is  obvious  when  we  consider  that  Visceral 
Impressions  carry  with  them  no  tendency  or  need  to  evoke 
the  activity  of  merely  one  side  of  the  body.  So  far  as 
they  pass  to  the  Cerebrum,  and  excite  the  action  of  '  organs 
of  relation,'   they   would  aj^pear  to  act  only  through  the 

*  "The  Human  Brain,"  Macmillan's  Magazine,  Nov.  1865. 
The  same  view,  it  appears,  was  put  forward  by  Dr.  Carpenter  in 
the  BriL  ^  For,  Med.  Chir.  Review  for  Oct.  18-iti. 


Chap.  XXV.]  PHRENOLOGY  :    OLD    AND    NEW.  5l7 

intermediation  of  impressions  from  the  Special  Senses, 
the  centres  of  which  have  been  awakened  and  rendered 
more  receptive  by  being  brought  into  relation  with  distinct 
though  '  unconscious  '  Visceral  Impressions. 

It  would  seem,  indeed,  from  some  observations  which 
have  been  already  made,  that  in  many  cases  of  Hemi- 
ansesthesia,  the  viscera  remain  at  least  as  tender  as  ever 
under  firm  pressure  upon  both  sides  of  the  body  ;  and 
this,  of  course,  would  indicate  that  the  cerebral  channels 
for  these  impressions  do  not  intermix,  in  the  region  of 
the  *  internal  capsule,'  with  those  of  other  modes  of  sen- 
sibility. 

And,  though  their  so-called  *  Centres '  may  also  be  dif- 
ferently situated,  it  is  pretty  certain  that  Visceral  Im- 
pressions must  either  radiate  into,  or  be  brought  into 
intimate  connection  with,  some  parts  of  the  province  of 
each  of  the  Special  Senses,  since  they  all  so  frequently 
interact  in  the  manner  already  referred  to.  The  inter- 
action does  not,  however,  only  take  place  in  one  direction. 
There  is  on  the  part  of  the  '  Sexual  Appetite,'  as  Prof. 
Bain  points  out,  "a,  many-sided  susceptibility  to  inflam- 
mation, through  all  the  senses,  through  the  trains  of 
thought,  and  through  emotions  that  are  not  sensations.'* 
To  a  less  extent  a  similar  '  inflammability '  by  means  of 
sensorial  impressions  also  obtains  in  regard  to  the  '  Ap- 
petite for  Food.* 


CHAPTER   XXYI. 

WILL    AND   VOLUNTARY   MOVEMENTS. 

"We  find  in  ourselves,"  says  Locke  (1690),  **  a  Power  to 
begin  or  forbear,  continue  or  end  several  Actions  of  our 
Minds  and  Motions  of  our  Bodies,  barely  by  a  Thought 
or  preference  of  the  Mind." 

Here  the  scope  of  that  ability,  which  goes  by  the  name 
of  '  Will '  or  '  Volition,*  is  clearly  enough  marked  out 
by  one  who  may  be  styled  the  father  of  our  modern 
Psychology. 

In  regard  to  the  second  of  the  spheres  above-mentioned 
for  the  exercise  of  Will,  viz.,  its  influence  over  "  the 
Motions  of  our  Bodies,"  Locke  ventured  upon  no  details; 
and  even  at  a  much  later  period  Hume  (1747)  was  still 
only  able  to  proclaim  the  complete,  and,  as  he  thought, 
hopeless  ignorance  which  reigned  thereon.  "  The  motion 
of  our  bodies,"  he  said,  **  follows  upon  the  command  of 
our  Will.  Of  this  we  are  every  moment  conscious.  But 
the  means  by  which  this  is  effected ;  the  energy  by  which 
the  Will  performs  so  extraordinary  an  operation ;  of  this 
we  are  so  far  from  being  immediately  conscious,  that  it 
must  ever  escape  our  diligent  inquiry." 

Hartley,  in  his  *'  Observations  on  Man,**  published 
only  one  year  later  than  Hume's  "Inquiry,"  made,  how- 
ever, some  valuable  and  very  sagacious  remarks  on  the 
causes,  modes  of  acquisition,  and  mutual  relations  of  the 


Chap.  XXVL] 

different  kinds  of  Movements  which  we  are  capable  of 
executing.  So  just  were  his  observations  that  they  still 
represent  the  basis  of  -our  knowledge  on  this  subject. 

Hartley  sought  also,  though  with  less  success,  to  make 
a  first  rough  classification  of  Movements,  from  the  point 
of  view  of  the  mental  state  or  process  by  which  they  were 
preceded,  when  he  said : — *'  Of  the  two  sorts  of  Motion, 
viz.,  Automatic  and  Voluntary,  the  first  depends  upon 
Sensation,  the  last  upon  Ideas." 

This,  even  apart  from  certain  necessary  qualifications 
which  Hartley  would  have  himself  assented  to,  cannot  be 
regarded  as  a  very  correct  generalization.  Some  auto- 
matic actions,  such  as  those  of  the  Heart,  Intestines,  and 
other  viscera,  are  due  to  '  unfelt '  Impressions  which  can 
scarcely  be  called  Sensations  ;  whilst  others  are  incited  by 
those  '  internally  initiated  '  feelings  known  as  Emotions-^- 
which  are  more  akin  to  Ideas  than  to  Sensations.  Again, 
Ideas  are  sometimes  provocative  of  automatic  movements, 
as  when — to  name  only  one  of  the  best  instances — a  ludi- 
crous Idea  impels  us  to  Laughter ;  though  in  multitudes 
of  other  instances  it  is  perfectly  true  that  Ideas  are  the 
primary  inciters  of  Voluntary  Movements.  Between 
these  extremes,  moreover,  numerous  insensible  grada- 
tions are  to  be  met  with  :  we  have  movements,  for 
instance,  that  are  scarcely  to  be  termed  Automatic,  and 
yet  which  physiologists  have  also  deemed  desirable  to 
mark  off  from  the  category  of  strictly  Voluntary  Move- 
ments— as  they  have  shown  by  their  application  to  them 
of  the  epithet  '  Ideo-motor.' 

That  actions,  which  are  at  first  Voluntary,  tend,  after  a 
time,  when  frequently  repeated,  to  become  truly  Automatic, 
Hartley  was,  of  course,  fully  aware.  It  was  he  who  first 
proposed  to  class  such  actions  as  '  Secondary  Automatic,' 
ii)  opposition  to  those  of  his  '  Primary  Automatic  '  category 


550  WILL    AND 

■ — including  under  this  latter  head  actions  which  the  in- 
dividual has,  from  the  first,  performed  automatically.  He 
endeavoured  to  formulate  some  of-  the  grounds  for  dis- 
tinguishing Voluntary  Actions  from  those  which  are,  as 
he  says,  "  to  he  esteemed  less  and  less  voluntary,  semi- 
voluntary,  or  scarce  voluntary  at  all." 

This  latter  subject  was,  however,  discussed  more  effec- 
tively, at  a  later  period,  by  James  Mill.  It  is  one  of 
considerable  importance,  since  it  involves  an  attempt  to 
discover  the  real  nature  or  elementary  constituents  of  that 
phase  of  Mind  which  we  name  Volition.  On  this  subject 
James  Mill*  advances  the  following  opinions: — 

"There  appears  no  circumstance  by  which  the  cases  called 
voluntary  are  distinguished  from  the  involuntary,  except  that  iu 
the  voluntary  there  exists  a  Desire.  Shedding  tears  at  the  hearing 
of  a  tragic  story  we  do  not  desire  to  weep;  laughing  at  the  recital 
of  a  comic  story  we  do  not  desire  to  laugh.  But  when  we  el^^vate 
the  arm  to  ward  off  a  blow,  we  desire  to  lift  the  arm;  when  we 
turn  the  head  to  look  at  some  attractive  object,  we  desire  to  move 
the  head.  I  believe  that  no  case  of  voluntary  action  can  be  men- 
tioned in  which  it  would  not  be  an  appropriate  expression  to  call 
the  action  'desired.'** 

If  there  is  interpolated,  therefore,  between  a  Sensation 
or  an  Idea,  and  the  Movement  which  it  may  evoke,  a 
feeling  of  an  emotional  order,  known  as  Desire,  a  move- 
ment which  would  otherwise  have  been  described  as 
'■  Sensory-motor  '  or  '  Ideo-motor,'  becomes  entitled  to  be 
known  as  a  Voluntary  Movement. f     This  is  the  first  and 

*  "  Analysis  of  the  Human  Mind,"  1830,  p.  279. 

t  Hartley's  view  was  very  similar.  He  says : — ■"  The  Will 
appears  to  be  nothing  but  a  desire  or  aversion,  sufficiently  strong 
to  produce  an  action  that  is  not  automatic,  primarily  or  secondarily 

The  Will  is,  therefore,  that  desire  or  aversion  which  is 

strongest  for  the  present  time."  Which  mental  mood  is  to  prevail 
18  sometimes  immediately  settled,  and,  at  other  times,  only  after  a 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  551 

most  important  distinction  drawn  by  James  Mill.  But, 
as  the  same  philosopher  afterwards  points  out,  something 
else  accompanies  or  immediately  follows  the  emotion  of 
Desire — viz.,  an  Idea  or  Conception  of  the  kind  of  Move- 
ment needed  for  the  gratification  of  the  Desire. 

It  seems  generally  admitted,  therefore,  by  the  philo- 
sophers above  quoted,  as  it  is  by  others,  that  the  motions 
of  our  bodies  are  begun,  continued  or  ended,  as  Locke 
put  it,  "barely  by  a  Thought  or  preference  of  the  Mind." 
Impressions,  Sensations,  Emotions,  Thoughts — these  are 
the  mental  states  which,  singly  or  in  combination,  are 
followed  by  Movements.  As  to  any  details  pertaining  to 
their  incitation  and  actual  accomplishment,  little  or 
nothing  more  is  known  with  any  degree  of  certainty. 
Writing  in  1830,*  James  Mill  said:  "We  do  not 
undertake  to  say  what  physical  links  are  between  the 
Idea  and  the  Contraction,  any  more  than  between  the 
Sensation  and  Contraction.  TJie  Idea  is  the  last  part  of 
the  Mental  ojoeration.'' 

If,  however,  this  be  really  so,  if  beyond  the  mental 
states  or  processes  above  enumerated,  we  have  in  Volun- 
tary Acts  mere  physical  changes  in  nerve  and  muscle,  as 
Hume  and  James  Mill  averred,  there  is  the  less  reason  for 
surprise  that  some  philosophers,  such  as  Dugald  Stewart 
and  Dr.  Thomas  Brown,  should  have  deliberately  omitted 
to  discuss  '  Will '  as  a  distinct  section  of  our  Conscious 
Life.    "  To  know  all  our  sensitive  states  or  affections,"  the 

process  of  Deliberation,  and,  concerning  this  process,  Hobbes  says: 
— "  The  whole  sum  of  desires,  aversions,  hopes  and  fears,  continued 
till  the  thing  be  either  done  or  thought  impossible,  is  what  we  call 

Deliberation.'^ "  Appetite,   therefore,   and   aversion    are 

simply  so-called  as  long  as  they  follow  not  deliberation.     But  if 
deliberation    have   gone  before,  then  the  last  act  of  it,   if  it  be 
appetite,  is  called  will ;  if  aversion,  unwilUnguess." 
*  Loc  cit.  11.  p.  266. 


652  WILL    AND 

latter  says,*  *'  all  our  intellectual  states,  all  our  Emotions, 
is  to  know  all  the  states  or  phenomena  of  the  Mind." 
The  precedence  of  one  or  other  of  these  subjective 
phases,  or  of  compound  conditions  derived  therefrom, 
would  correspond,  as  he  thought,  to  what  we  know  as 
*  Will.'  Beyond  these  subjective  phases,  we  should  pass  in 
the  execution  of  Voluntary  Movements  from  the  sphere  of 
psychology  into  that  of  physiology  pure  and  simple. 

The  distinctness  of  the  Idea  or  Conception  of  the  Move- 
ment (which  we  shall  presently  find  to  be  of  complex 
origin),  as  one  of  the  Conscious  Components  of  a  Voli- 
tion, will  be  found  to  vary  much  with  the  degree  of 
familiarity,  or  ease  of  execution,  of  the  Movement.  And 
in  this  latter  respect,  of  course,  all  gradations  exist  be- 
tween the  simplest  kinds  of  Voluntary  Movements  and 
those  of  the  most  complex  order. 

We  may,  for  instance,  *  voluntarily  '  perform  some  move- 
ment which  frequent  repetition  has  already  made  easy, 
but  which,  for  the  most  part,  we  now  perform  '  auto- 
matically.' The  fingers  of  a  sleeping  child  may  close 
over  an  object  gently  brought  into  contact  with  its  palm  ;- 
or  when  awake  the  child  may  excite  a  similar  movement 
voluntarily.  An  object  brought  close  to  the  eyes  may 
cause  a  person  to  wink  involuntarily,  but  he  is  also  capable 
of  performing  the  same  act  in  a  voluntary  manner.  We 
may  lift  the  arm  instinctively  to  ward  otf  an  impending 
blow,  or  we  may  raise  it  in  the  same  manner  voluntarily. 
In  all  such  cases  the  Idea  or  Conception  of  the  Movement 
needed  scarcely  obtrudes  itself  at  all  "as  a  conscious 
element  of  the  '  Volition  ' ;  this  is  a  part  of  the  process 
which  has  here  become  more  or  less  latent. 

But  in  the  other  more  complex  category  of  Voluntary 
♦  "Philosophy  of  the  Human  Mind,"  Lect.  xvii. 


Chap.  XXVL]  VOLUNTARY    MOVEMENTS.  553 

Actions,  efforts  are  made  to  perform  some  new  combina- 
tions of  movements,  the  complicacy  of  which  renders  them 
at  first  very  difficult  to  execute.  This  is  the  case,  for 
instance,  when  a  child  is  learning  to  write,  or  when  a 
youth  is  learning  to  dance  or  to  play  upon  some  musical 
instrument.  In  every  such  case,  some  Idea  or  Concep- 
tion of  the  kind  of  Movement  iieeded  is  to  be  recog- 
nized as  a  more  or  less  distinctly  conscious  component  of 
the  '  Volition  '  in  question. 

When  commencing  a  Voluntary  Movement  which  we  have  often 
previously  executed,  we  initiate  it  with  certain  pre-deterniined 
qualities  almost  intuitively  given  to  it,  and  yet  in  the  selection  of 
which  we  are  evidently  guided  by  past  experience  and  education. 
A  simple  case  will  illustrate  this.  I  know  that  objects  having 
certain  visual  characters  have  usually  given  me  certain  impressions 
of  'weight'  and  'resistance'  when  I  have  previously  handled 
them ;  and,  therefore,  this  previous  experience  enables  me,  on  seeing 
such  an  object  again  and  desiring  to  handle  it,  to  conjure  up  a 
•  conception  '  of  the  Movement  needed,  which,  though  it  may  be 
very  indistinctly  realized  in  Consciousness,  enables  me,  in  some 
way,  to  give  the  Volitional  Act  its  necessary  qualifications. 

This  power,  partly  instinctive  and  partly  a  result  of  individual 
education,  has  been  made  the  subject  of  much  mystification. 
Some  ascribe  it  to  a 'locomotor  instinct,'  pure  and  simple,  and 
thereby  ignore  the  fact  that  it  is  a  power  the  manifestation  of 
which  is  greatly  regulated  by  individual  education.  Some  appeal 
with  vague  gravity  to  the  intervention  of  what  they  term  '  motor 
intuitions' — meaning,  thereby,  something  pertaining  to,  or  having 
their  origin  in,  the  Motor  Centres  about  to  be  called  into  activity, 
but  which  yet,  beforehand,  in  some  way  help  to  determine  the 
mode  of  their  own  activity.* 

*  There  are,  in  all  probability,  in  Motor  Centres  multitudes  of 
different  combinations  of  cell-and-fibre  connections  which  have 
been  gradually  established,  and  throngh  the  agency  of  which  Voli- 
tional Incitations  may  be  necessarily  distributed  along  certain  '  out- 
going '  fibres,  so  as  to  call  into  activity  in  definite  modes  particu- 
lar  groups   of  Muscles.     There  seems  no  good  reason,  howevtT, 


554  WILL    AND 

James  Mill  held,  witli  more  show  of  reason,  that  what  have  been 
commonly  termed  'Muscular  Sense' impressions  intervene,  and  come 
into  joint  operation  as  determining  agents,  at  a  stage  immediately 
posterior  to  the  Conception  above  referred  to,  and  anterior  to  the 
actual  occurrence  of  the  Voluntary  Movement.  If  we  substitute 
for  these  so-called  *  muscular  sense' impressions,  our  Kincesthetio 
Impressions,*  we  may,  on  such  broader  terms,  adopt  this  view  of 
James  Mill  as  fairly  typifying  the  probable  mode  of  execution  of, 
or  rather  order  of  procest;es  involved  in,  the  initiation  of  Yoluntary 
Movements. 

The  same  parts  of  the  Brain  as  are  called  into  play  for  the 
initiation  of  any  set  of  Yoluntary  Movements  would  probably 
remain  in  activity  during  the  continuance  of  such  movements, 
though  perhaps  not  exactly  in  the  same  relative  2:»roportions.  Thus 
an  *  ideal'  recall  or  'conception'  of  the  sensory  qualities  of  the 
Movements  needed  operates  as  the  starting  point,  enabling  the  indi- 
vidual, from  an  already  existing  and  in  part  instinctive  basis,  to 
determine  liow  to  act  and  ivliat  force  to  emijloy ;  whilst,  during  the 
continuance  of  the  Movements,  he  would  be  also  partly  influenced 
by  actual '  sensations  '  realizing  themselves  in  the  same  parts  of 
the  Brain,  and  telling  him  how  he  is  acting  and  tvhat  force  he  is 
employing.f  Yet  in  the  two  cases,  the  relative  amount  of  activity 
of  the  sensory  centres  concerned  may  not  be  equal. 

Thus,  if  we  suppose  the  centres  specially  called  into  activity  as 
guiding  centres  to  be  the  Yisual  and  the  Kinsesthetic,  it  may  be  that 
the  former  has  the  dominating  influence  in  the  production  of  the 
initial  Conception;  whilst,  during  the  continuance  of  the  Move- 
ments, impressions  impinging  upon  the  Kinsesthetic  Centres  may, 
in  their  turn,  have  a  more  potent  guiding  influence.  If  a  person 
should  attempt  to  take  from  a  table  a  small  bundle  of  cotton  wool 

why  any  such  organizations,  or  rather  the  functional  activity  of 
such  organizations,  should  be  spoken  of  as  *  motor  intuitions,'  or 
why  these  should  be  deemed,  as  Dr.  Maudsley  says  ("  Physiology 
and  Pathology  of  Mind,"  in  Chap,  on  'Motor  Centres'),  to  con- 
stitute an  "  important  motorial  region  of  mental  life  " — whatever 
that  may  mean.  Dr.  Maudsley's  views  on  this  subject  do  not  seem 
to  be  very  clearly  realizable,  though  his  Chapter  on  •Yolition* 
is  extremely  good  and  free  from  all  ambiguity. 

*  See  p.  543. 

t  See  Appendix. 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  555 

into  the  middle  of  whicli,  unknown  to  him,  a  heavy  leaden  weight 
had  been  introduced,  his  initial  determination  of  the  Movement 
deemed  to  be  adequate  would  need  rectification,  and  in  such  a  case 
it  would  certainly  be  rectified  in  the  main  at  the  instigation  of 
Kinsesthetic  Impressions. 

Hitherto  reference  has  been  made  to  the  simpler  class  of  Yolun- 
tary  Movements — to  those  in  which  the  movements  themselves  are 
familiar  or  easy  of  execution.  But  where  the  movements  which  it 
is  desired  to  execute  are  complex  and  difficult,  and  we  have  to  learn 
them  by  imitation  of  the  movements  of  other  persons,  the  sense 
of  Sight  is  then  doubly  brought  into  play.  It  is  necessary  at  the 
commencement,  and  during  the  continuance,  of  our  efforts  to 
copy  such  movements,  to  look  alternately  at  our  model  and  at 
our  own  moving  members.  A  long  time  and  much  practice  is,  in 
fact,  required  before  a  person  learning  to  dance,  or  to  play  upon 
some  musical  instrument,  is  able  to  execute  either  of  these  actions 
without  the  aid  from  moment  to  moment  of  guiding  Sight  impres- 
sions. "  In  learning  to  dance,"  as  Hartley  says,  "  the  scholar 
desires  to  look  at  his  feet  and  legs,  in  order  to  judge,  by  seeing, 
when  they  are  in  a  proper  position.  By  degrees  he  learns  to  judge 
of  this  by  feeling ;  but  the  visible  idea  left  partly  by  the  view  of 
his  master's  motions,  partly  by  that  of  his  own,  seems  to  be  the 
chief  associated  circumstance  that  introduces  the  prosper  motions.** 
During  the  process  of  learning,  therefore,  the  Visual  Centre  evi- 
dently exercises  a  dominating  influence. 

In  time,  however,  the  impresf-ions  pertaining  to  the  '  Sense  of 
Movement '  (which  are,  of  course,  always  to  some  extent  associated 
with  those  of  Sight)  become,  by  way  of  their  organized  channels, 
sufficiently  freely  associated  with  them  and  with  the  newly  organ- 
izing '  motor  '  nerve  channels  and  mechanisms,  to  permit  the  Move- 
ments we  have  been  practising  to  be  performed  under  the  immediate 
guidance  of  Kina3sthetic  Impressions  only — without  further  neces- 
sity for  a  conjoint  direction  through  the  sense  of  Sight.  As  Jaccoud, 
however,  points  out  {Les  parapZ^'^/zes  et  Vataxie,  p.  601)  the 
sensorium  requires  to  learn,  in  the  first  instance,  what  conditions 
and  positions  of  the  moving  parts  are  related  to  such  and  such 
tactile  and  other  impressions  coming  from  them  And  thus  it  is 
only  at  the  termination  of  this  apprenticeship  that  it  is  enabled  to 
conclude  directly  from  KinaBsthetic  Impressions  as  to  the  precise 
conditions  of  the  moving  parts.  This  process  of  education  can  only 
proceed  correctly  by  reason  of  the  comparisons  which  we  are  accus- 
tomed to  make  from  moment  to  moment,  between  the  positions  and 


556  WILL    AND 

movements  of  the  limbs  as  revealed  to  Sight,  and  the  sum  total 
of  Kina3sthetic  Impressions  simultaneously  received  from  the  same 
parts. 

This  kind  of  education  being  once  completed  in  regard  to  any  par- 
ticular Movements,  the  knowledge  subsequently  derivable  through 
the  Kinsesthetic  Centre  becomes  as  real  and  as  capable  of  passing 
over  into  appropriate  action  as  that  previously  coming  through 
the  Visual  Centre.  Thereafter  its  impressions  alone — even  when 
they  very  imperfectly,  or  not  at  all,  rouse  our  Consciousness  of  their 
existence — suffice  to  inform  us  (that  is,  suffice  to  excite  the  proper 
Cerebral  '  centres '  in  ways  definitely  related  to  different  positions 
and  tensions)  as  to  the  exact  position  of  our  limbs,  and  as  to 
the  nature  and  degree  of  their  Movements.  It  is  by  Kineesthetic 
Impressions  that  we  are  afterwards  continually  instructed  as  to  the 
qualities  of  the  Movements  actually  produced ;  through  them  we 
know  whether  to  continue  with  our  present  mode  of  action,  or 
whether,  the  better  to  attain  the  desired  end,  the  quality  of  the 
*  Volition  '  should  be  altered.  And  if,  during  the  execution  of  a  com- 
plex Movement,  any  alteration  should  be  desired  in  respect  to  one 
of  its  'volitional '  qualities — that  is,  either  as  regards  the  strength, 
the  rapidity,  the  direction,  or  the  continuance  of  one  of  its  com- 
ponent motions,  this,  "  barely  by  a  Thought  or  preference  of  the 
Mind,"  can  be  immediately  effected,  though  the  great  majority  of 
mankind  would  have  no  knowledge  whatsoever  of  the  nature  and 
degree  of  the  individual  changes  brought  about  in  the  actions  of 
the  different  Muscles  concerned. 

The  mode  of  acquisition  above  indicated  seems  well  to  accord 
with  our  other  interests  and  with  the  daily  necessities  of  our  Life. 
The  sense  of  Sight  greatly  facilitates  the  process  of  learning,  and 
its  vivid  impressions  speedily  enable  the  '  sensorium  '  to  appreciate 
aright  the  meaning  of  the  more  vague  and  occult  impressions 
coming  to  it  simultaneously  through  the  '  sense  of  Movement.' 
Soon,  however,  the  Visual  Sense,  which  we  need  for  so  many  other 
important  purposes,  no  longer  requires  to  be  concentrated  merely  on 
the  performance  of  Movements.  Later  still,  our  '  attention '  or 
Consciousness  becomes  further  freed  from  disturbing  details  con- 
nected with  Movements.  The  possibly  conscious  impressions  per« 
taining  to  the  'sense  of  Movement'  at  last  habitually  pass  un- 
heeded, and  then  we  come  to  perform  multitudes  of  daily  actions 
under  the  guidance  of  mere  '  unconscious  '  Kina3sthetic  Impressions. 

Thus  the  working  of  the  '  motor'  side  of  our  complex  nervous- 
mechanism,  even  when  it  is  concerned  in  executing  the  behests  oi 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  557 

*  Will,'  proceeds  so  smoothly,  and  is  practically  so  much  unheeded 
as  to  leave  us  free  to  follow  up  the  threads  of  our  Conscious  Life 
unhindered  by  the  multitudinous  details  pertaining  to  the  varying 
states  of  innumerable  Muscles  acting  in  ever-changing  combina- 
tions. We  may  truly  be  thankful  that  we  have  not  in  reality  any 
such  'muscular  sense,'  as  some  psychologists  imagine  for  them- 
selves, and  that  even  in  Voluntary  Movements  the  Mind  knows 
nothing  concerning  the  Nerves  or  the  Muscles  by  the  intervention 
of  which  the  processes  are  accomplished. 

From  our  own  individual  experience,  as  well  as  from 
what  has  been  above  set  forth,  it  would  appear  obvious 
that  careful  practice  alone  is  needed,  in  order  that  pre- 
viously strange,  difficult,  and  complex  Movements  should 
be  capable  of  being  performed  with  ease  ;  and  that,  after 
a  time,  during  the  process  of  learning,  first  the  '  Concep- 
tion '  of  the  Movements  needed,  and  subsequently  the 
Desire  which  originally  prompted  to  their  execution,  may 
alike  vanish  as  conscious  states  by  which  they  are  neces- 
sarily preceded.  When  this  latter  stage  of  perfection  has 
been  achieved,  the  actions  previously  'Voluntary,'  in  the 
strictest    sense    of   the   term,    become    promoted   to   the 

*  Secondary  Automatic '  category,  since  the  occurrence  of  a 
Sensation,  an  Emotion,  or  an  Idea  may  be  immediately, 
and  without  the  intervention  of  any  other  conscious  state 
whatsoever,  succeeded  by  one  of  the  complex  Movements 
in  question.  Thus  Movements,  the  possibility  of  perform- 
ing which  has  been  slowly  and  with  so  much  difficulty 
acquired  by  the  individual,  have  now,  in  fact,  become 
almost  as  easy  for  us  as  sucking,  swallowing,  coughing,  or 
any  other  of  those  '  Primary  Automatic  '  actions,  the  power 
of  performing  which  was  born  with  us — as  an  inheritance 
from  untold  generations  of  human  and  other  ancestors. 

In  many  cases,  indeed,  there  is  good  reason  for  believ- 
ing that  the  alliance  between  '  Primary  Automatic  '  and 
some  '  Secondary  Automatic  '  actions  is  even  more  funda- 


558  WILL    AND 

mental  than  has  been  above  indicated.     The  reasons  for 
this  opinion  must  be  set  forth  in  detaiL 

The  Mechanisms  for  Primary  Automatic  Movements, 
and  their  Modes  of  Origin. 

The  nervous  connections  representative  of  a  certain  number  of 
Movements  which  have  been  commonly  performed  by  the  present 
and  many  past  generations  of  any  race  of  animals  exist  in  an 
organized  condition  in  the  Spinal  Cord  and  Medulla  of  such  animals. 
They  are  represented  by  the  development  of  certain  cell-and-fibre 
connections  in  the  anterior,  or  what  are  known  as  the  '  motor  * 
regions  of  the  Grey  Matter  of  these  parts — such  mechanisms  being 
in  continuity  in  front  with  the  roots  of  '  outgoing'  nerves,  and  in 
relation  behind  with  groups  of  smaller  nerve  cells  with  which  the 
'ingoing  '  nerves  of  the  posterior  roots  are,  in  their  turn,  in  some  sort 
of  structural  relation.  It  is  along  these  latter  channels  that  the 
sensory  Impressions  prompting  to  the  Movements  of  which  we 
have  been  speaking  reach  the  Spinal  Cord  or  Medulla  * 

Many  of  the  corresponding  groups  of  '  motor '  Cells,  situated  at 
the  same  level  in  the  right  and  left  halves  of  the  Cord  and  Medulla, 
are  intimately  connected  by  transverse  *  commissural '  fibres— in 
fact,  wherever  joint  action  of  the  nerve  units  on  the  two  sides  is 
a  matter  of  common  occurrence  (fig.  154,  o  o'). 

Many  of  the  groups  of  motor  cells,  at  different  levels  of  the 
cord  are  also  connected  with  one  another  into  single  or  multiple  com- 
binations, by  longritudinal  'commissural'  fibres  whose  length  varies 
according  to  the  distance  apart  of  the  cell  groups  thus  united  for 
conjoint  activity.  These  longitudinal  connecting  fibres  of  different 
lengths,  as  they  pass  from  cell- group  to  cell-group,  have  been 
ascertained  (on  the  basis  of  clinico-pathological  evidence  supplied 
by  persons  suffering  from  spinal  disease)  to  traverse,  in  part  at 
least,  the  'posterior  columns'  of  the  Cord. 

Bilateral  groups  of  these  cells,  existing  at  various  levels  in  the 
two  '  anterior  cornua,'  though  differing  much  from  one  another  in 
the  number  of  the  units  involved  and  in  the  width  of  the  area  over 
which  they  are  distributed,  are  conceived  to  be  the  Spinal  and 
Medullary  Nervous  Mechanisms  needful  for  the  execution  of  avast 
multitude  of  Reflex,  or  Primary  Automatic  Movements,  also  of  all 

*  See  pp.  26,  52. 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS. 


559 


— —       ~:«^ 


Fig.  178.— Groups  of  Cells  in  connection  with  the  Anterior  Roots  of  the  Spinal 
Nerves,  a§  seen  in  a  transverse  section  through  one  of  the  Anterior  Cornua  in  the 
Spinal  Cord  of  a  Sheep.  (Flint  after  Dean.)  A.  Emergence  of  the  anterior  roots 
from  the  Cornua  of  Orey  Matter;  b,  b,  b  Cells  connected  with  one  another  by  long, 
slender,  '  intercellular '  processes,  and  also  with  the  fibres  of  the  Anterior  Roots. 
Bundles  of  fibres  are  seen  crossing  one  another  in  almost  every  directioa. 


660  WILL    AND 

degrees  of  complexity.  It  is  probably  because  these  several  cell- 
and-fibre  mechanisms  are  so  perfect  in  their  arrangement,  that 
each  one  of  the  Movements  in  question  is  capable  of  being  evoked 
■with  machine-like  regularity  in  response  to  appropriate  stimuli 
im-pinging  upon  and  passing  through  them.* 

The '  mechanisms '  for  the  production  of  many  of  such  Movements 
may  have  been  originally  developed  far  back  in  the  history  of  our 
race  or  of  antecedent  races.  But  others  of  them — those,  for  in- 
stance, which  are  concerned  in  the  acts  of  Deglutition — however 
much  they  may  have  been  from  time  to  time  modified  in  detail, 
must  have  been  originally  organized  in  creatures  the  combination 
of  whose  vague  efforts  and  desires  would  scarcely  be  considered  to 
produce  anything  like  what  we  know  as  'Volition.'  In  all  prob- 
ability such  feelings  and  the  power  of  concentrating  Attention, 
which  is  their  indispensable  correlative,  only  gradually  attain  to 
the  degree  of  precision  and  intensity  of  which  we,  as  human  beings, 
are  conscious.  This  would  probably  be  conceded  by  all,  and  if  so 
it  must  be  concluded  that  the  organic  nervous  bases  of  many  of 
the  Primary  Automatic  Movements  of  higher  animals  have  had 
their  orig-in,  or  have  come  into  being,  independently  of  anything 
like  such  an  agency  as  that  which  we  know  as  'Volition.' 

Thus,  the  further  back  we  go  in  the  animal  series,  the  more 
vague,  in  all  probability,  would  be  the  influences  prompting  to  new 
developments  of  Nerve  Tissue  which  could  be  ranged  under  the  '  Vo- 
litional '  type,  and  the  more  we  should  be  compelled,  if  we  strive  to 
learn  the  causes  of  such  new  developments,  to  fall  back  upon  those 
obscure  hut,  nevertheless,  'potent  oric/mal  tendencies  or  conditions, 
tinder  the  influence  of  which  the  first  rudimentary  Nerve  Elements 
hecame  developed  in  the  tissues  of  loiver  Organisms  (p.  19). 

This  mere  organic  nisus,  or  set  of  vital  conditions,  favouring  the 
first  differentiation  of  Nervous  Tissues,  would  probably  continue  to 
act  as  the  most  potent  influence  governing  all  future  phases  of 
their  development — though  it  seems  evident  that  such  develop- 
mental proclivities,  even  in  the  Spinal  Cord,  are  capable  of  being 
favoured  in  some  mysterious  manner  by  Cerebral  Influence  when 
'  Volition  '  is  strongly  exercised — that  is  when  a  sensorially  active 
Brain  is  dominated  in  such  ways  as  to  be  productive  of  certain 

*  That  Hartley  (1748)  distinctly  realized  and  foresaw  the  nature 
of  what  we  now  term  *  Keflex  Actions,'  seems  evident  from  a  paa- 
eage  in  his  **  Observations  on  Man,"  Prop.-xviii. 


CirAP.  XXVI.]  VOLUNTARY    MOVEMENTS.  561 

*  Desires,'  and  further  influenced  in  certain  correlative  tracts  by 
that  mode  or  degree  of  activity  which  on  its  subjective  side  we 
call  '  Attention.' 

Deferred  Primary  Automatic   Movements. 

Much  difference  exists  among  different  Animals  as  to  the  degree 
of  perfection  at  the  time  of  hirth  of  these  inherited  cell -and- fibre 
connections,  and,  therefore,  similar  differences  exist  among  such 
Animals,  in  regard  to  their  power  at  birth  of  executing  the  several 
Movements  with  which  such  Nervous  Mechanisms  are  in  relation. 

Thus,  in  some  Birds  at  the  time  of  their  emergence  from  the 
egg,  and  in  some  Quadrupeds  at  birth,  much  of  the  nervous 
mechanisms  concerned  with  Automatic  Movements  habitually  per- 
formed by  such  creatures,  are  so  far  perfected  that  these  animals 
are  capable  almost  at  once  of  performing  tho  most  complex  Move- 
ments— without  in  any  way  requiring  to  'learn'  how  to  execute 
them.  The  experiments  of  D.  A.  Spalding  with  Chickens  and 
young  Pigs  have  revealed  interesting  facts  in  illustration  of  this 
position  (see  pp.  188,  229). 

Many  instances  of  an  opposite  character  may,  however,  be  cited 
— cases,  that  is,  in  which  at  the  time  of  emergence  from  the 
egg,  or  at  the  time  of  birth,  other  Birds  or  Mammals  are  in  a  much 
less  mature  state  of  development,  and  in  which  their  powers  of 
executing  complex  Movements  of  a  similar  order  are  notably  less 
advanced. 

The  young  of  Canaries  and  many  other  birds,  for  instance, 
remain  for  ten  days  or  a  fortnight  unable  to  feed  them.selves  or  to 
walk,  and  they  may  continue  tor  nearly  twice  this  time  unable  to 
fly.  But  this  backwardness  in  power  of  executing  such  Move- 
ments, is  obviously  only  one  of  the  signs  or  accompaniments  of 
their  generally  backward  condition  of  development.  A  bird  can  no 
more  fly  without  the  aid  of  properly  developed  internal  Nervous 
Mechanisms  than  without  wing-feathers,  and  the  one  set  of  struc- 
tures are  probably  almost  as  abortive  as  the  other  in  young 
Canaries  and  in  the  young  of  other  birds. 

The  performance  of  many  Movements  that  are  '  primarily ' 
Automatic  in  the  Chick  and  birds  like  it,  are,  therefore, 
deferred  in  Canaries  and  their  allies  till  such  times  as  the  related 
nervous  and  other  mechanisms  have  had  time  to  develop.  Ground 
is  thus  given  for  the  supposition,  commonly  entertained,  that  such 


562  WILL    AND 

creatures  have  to 'learn 'how  to  perform  these  Movements — which, 
if  true,  would  make  it  necessary  to  classify  them  as  'secondary* 
rather  than  'primary'  Automatic  Movements. 

The  valuable  experiments  of  Spalding  with  young  Swallows  and 
other  birds  that  emerge  from  the  egg  in  an  immature  condition 
have,  however,  shown  that  in  them  the  manifestation  of  *  primary* 
Automatic  Movements,  dependent  upon  inherited  Nervous  Mecha- 
nisms, is  merely  deferred  till  the  time  when  such  developments 
have  been  achieved — and  that  then,  without  any  process  of  '  learn- 
ing,' the  Movements  are  readily  capable  of  being  evoked  (p.  230). 

The  helpless  condition  of  the  infant  Monkey  and  of  the  Human 
Infant  at  birth  are  similarly  to  be  ascribed,  in  great  part,  to  the 
immature  condition  of  their  great  Nervous  Centres  at  this  period. 
Many  of  the  Movements  which  they  slowly  '  learn '  to  perform  are 
doubtless  rendered  possible  by,  and  acquired  coincidently  with,  the 
actual  development  of  those  nerve  cells  and  fibres  in  the  Spinal 
Cord  and  Medulla  which  are  instrumental  in  the  execution  of  such 
Movements.  Thus,  when  we  say  that  the  young  child  '  learns  '  to 
perform  these  movements,  it  should  be  understood  that  this  word 
is  here  applicable  only  in  a  very  qualified  sense.  Its  vague  efforts 
serve,  perhaps,  merely  as  incitations  tending  to  arouse  or  perfect 
the  already  existing  (because  inherited)  tendencies  to  development 
of  certain  Motor  and  other  Nerve  Centres— of  mechanisms,  that 
is,  which  in  many  other  creatures  have  reached  their  full  term  of 
development  by  or  almost  immediately  after  birth. 

But  for  the  existence  of  this  organic  nisus  (in  the  form  of  an 
inherited  tendency  to  develop  in  certain  modes  and  directions)  the 
Human  Infant  coald  never  so  readily  as  it  does  acquire  the  power 
of  executin^r  the  excessively  complex  Movements  which  are  con- 
cerned in  Standing,  in  Walking,  or  in  Articulate  Speech  (see  p.  607). 

Relations  of  Voluntary  and  Automatic  Movements. 

The  complex  movements  last  referred  to  being  some  of  the  most 
typical  of  the  'secondary'  Automatic  Movements  of  Hartley,  the 
above  considerations  will  suffice  to  show  that  many  of  those 
hitherto  placed  in  this  category,  are  but  '  primary '  Automatic 
Movements,  the  power  of  executing  which  has  been  somewhat 
deferred.  Previously,  the  guiding  influence  of  Volition  has  been 
supposed  by  many  to  be  principally  instrumental  in  enabling  the 
child  to  execute  them,  whilst  here  it  is  contended  that  their  acquisi- 
tion by  the  individual  is  much  more  largely  dependent  upon  the 


OHAP.  XXVL]  VOLUNTARY    MOVEMENTS, 


563 


gradual  development  of  inherited  Nervous  Mechanisms — due  to  the 
successive  education  of  many  preceding  generations.  They  are 
clearly  not  new  Movements,  acquired  afresh  by  each  individual,  as 
would  be  the  case,  for  instance,  with  those  persons  who  learn  to 
swim,  to  dance,  or  to  play  upon  any  musical  instrument.  In  the 
one  set  of  cases  Yolitional  Efforts  are  met  more  than  half  way  by 
inherited  developmental  tendencies ;  whilst  in  the  other  set,  and 
in  the  case  of  all  new  Yolitional  Movements  acquired  by  adults, 
the  Volitional  Influences  are  aided  only  by  those  natural  organic 
proclivities  to  the  development  of  new  nervous  mechanisms,  which 
originally  (under  the  influence  of  suitable  stimuh)  led  to  the  pri- 
mary genesis  of  jSTerve  Tissues,  and  which  may  safely  be  deemed 
to  be  still  operative  in  all  animals,  whether  high  or  low. 
Classification  of  Movements. 


Movements 

Acquired  by  the 

Jndividaal. 


3Iovements 

Inherl'ed  by  tht 

Individual, 


L  Volitional. 


II.  Secondary 

Automatic. 

(Hartley.; 


III.  Primary 

Automatic. 


'a.  Wliere  the  Movements  them- 
selves are  familiar  and  easy. 

b.  Wliere  the  Movements  them- 
selves are  unfamiliar  and 
difficult. 

'a.  Movements  learned  by  each 
individual  for  himself  which, 
subsequently,  after  long 
practice  become  familiar  and 
easy  of  execution. 

b.   Movements  which    cq^^ear  to  a^ 
need  learning  by  each  indi- 
vidual, merely  because  their 
neivous  mechanisms  are  not 
developed  at  the    time    of 
birth. 
Movements  learned   by  ante-  b.  > 
cedent  generations  of  ani- 
mals, now  capable  of  being 
instinctively  performed    at 
birth,   owing   to    inherited 
mechanisms   being    at  this 
time  sufficiently  developed. 

Volitional  acts  are,  therefore,  merely  Automatic  acts  in  process 
of  formation,  first  of  all  for  the  Individual,  and  subsequently,  it 
may  be,  for  the  Race.  Where  such  Movements  have  been  acquired 
or  learned  for  the  Race,  unless  the  inherited  correlative  IS'ervous 
Mechanisms  are  developed  at  the  time  of  birth,  Yolitions  may  in 
each  Individual  again  intervene  and  act  as  stimuli  during  the  time 
that  such  inherited  Mechanisms  are  undergoing  their  j^roper  degree 
of  development. 

Taking  the  Spinal  and  Medullary  Motor  Mechanisms 
ab  being  either  developed  or  in  process  of  development,  we 


564  WILL    AND 

may  now  turn  our  attention  more  particularly  to  a  con- 
sideration of  the  parts  whence,  and  of  the  channels 
through  which,  Cerebral  Incitations  pass  (on  their  way 
down  from  cortical  grey  matter)  in  Emotional,  Ideo-motor, 
or  Yolitional  Movements. 

One  part  of  the  route  has  been  pretty  clearly  ascertained, 
and  this  may  be  first  referred  to. 

From  the  evidence  supplied  by  disease  in  the  hum&y 
subject,  from  experiments  upon  some  of  the  lower  animals, 
and  from  other  sources  of  knowledge,  it  has  been  asce? 
tained  that  the  Corpora  Striata  are  great  motor  ganglisc 
in  some  way  concerned  with  the  execution  of  Voluntary, 
Emotional,  and  Ideo-motor  Movements. 

Motor  stimuli — that  is  stimuli  which  are  to  evoke 
movements — pass,  therefore,  from  certain  parts  of  the 
Cerebral  Cortex  downwards  to  the  corresponding  Corpora 
Striata.  These  bodies  are  called  into  activity  in  a  way 
which  cannot  be  defined,  though  from  them  the  motor 
stimuli  seem  to  be  continued  and  redirected  towards  the 
*  motor  mechanisms '  of  which  we  have  previously  been 
speaking,  in  the  Medulla  and  Spinal  Cord. 

The  tracks  of  these  latter  stimuli  are  fairly  well  known. 
They  pass  from  each  Corpus  Striatum  through  the  inferior 
layers  of  the  Crus  Cerebri,  and  through  the  Pons  Varolii  on 
the  same  side  ;  whilst  below  this  bridge  they  are  gathered 
together  in  the  '  anterior  pyramid '  of  the  Medulla,  which, 
after  a  course  of  a  little  more  than  one  inch,  decussates  in 
part  with  its  fellow — in  such  a  manner  that  many  of  the 
fibres  of  each  pyramid  pass  over  into  the  opposite  '  lateral 
column  '  of  the  Cord,*  whilst  some  continue  to  descend  on 

*  It  would  appear,  from  common  plienomena  occasioDed  by  disease 
of  the  great  Nerve  Centres  in  Man,  that  the  cerebral  channels 
through  which  limb-movements,  at  least,  are  called  into  activity, 
must  undergo  such  a  'decussation.* 


Chap.  XX VL] 


VOLUNTARY    MOVEMENTS. 


565 


the  same  side  in  tlie  '  anterior  column.'  The  motor  fibres 
which  decussate  and  pass  downwards  in  the  lateral  columns 
of  the  Spinal  Cord 
enter  the  anterior 
cornua  of  Grey  Mat- 
ter in  the  cervical, 
the  dorsal  or  the 
lumbar  region,  ac- 
cording to  the  situa- 
tion of  the  groups 
of  cells  concerned 
with  the  Movements 
which  the  particular 
cerebral  stimuli  tra- 
versing these  chan- 
nels are  destined  to 
evoke. 

The  passage  of 
Cerebral  incitations 
or  stimuli  through 
one  or  other  of  these 
Spinal  Mechanisms 
is  followed  by  an 
outpouring  of  grad- 
uated Molecular 
Movements  along 
certain  of  the  fibres 
of  the  '  anterior 
roots  '  with  which 
such  Mechanisms 
are  continuous  :  and 
these,  traversing  the 
Motor  Nerves  at  the 
rate  of  about  111  feet  per  second,  speedily  excite  definite 
25 


Fig.  179.— Nerve  Cell  with  many  branches  from 
one  of  the  anterior  Cornua  of  a  Hiiman  Spinal  Cord. 
(Max  Schultze.)  a,  Unbranched  Cell-process  passing 
into,  or  joining  the  axis  cylinder  of  one  of  the  '  ante- 
rior root '  fibres,  the  other  processes  being  branched  ; 
b,  an  aggregation  of  pigment-granules  on  one  side  of 
the  large  nucleolated  nucleus,     (x  150  diameters.) 


566 


WILL    AND 


groups    of   Muscles   in  definite  ways,  with  the    effect   of 
producing  the  desired  Movements. 

The  mode  in  which  physicians  and  pathologists  have 
acquired  this  knowledge  as  to  the  route  followed  by 
cerebral  stimuli  from  the  Corpora  Striata  downwards  to 
the  Muscles,  is  too  intricate  and  technical  to  be  here  dis- 
cussed.    We  must  content  ourselves  for  the  present  with 

the  above  simple 
statement  of  facts, 
in  addition  to  the 
following  brief  ex- 
planation. 

The  effects  resulting 
from  disease  of  the  Cor- 
pora Striata  in  man, 
whether  in  the  form  of 
Softening  or  Haemor- 
rhage, demonstrate  the 
importance  of  these 
bodies  in  relation  to 
Yoluntary  Movements, 
and  prove  that  they  have 
to  do  with  the  transmis- 
sion and  proper  distribu- 
tion of  '  volitional '  inci- 
tations.  The  destrnctinn 
or  serious  damage  of  one 
Corpus  Striatum  by 
disease  produces,  among 
other  results,  a  complete 
loss  of  voluntary  power 
over  the  Limbs  on  the  opposite  side  of  the  body  (Hemiplegia) — 
though  the  trunk  muscles  which  are  called  into  simultaneous  ac- 
tivity do  not  share  in  this  ]mralysis,  for  reasons  first  given  by 
Broadbent  (p.  480).  Each  Corpus  Striatum  transmits,  therefore, 
the  '  volitional  '  incitatioiis  for  the  Limb-movements  of  the  oppo- 
site half  of  the  body;   whilst  it  would  appear  that  either  of  them 


Fig.  180.— Transverse  section  of  the  Brain  of  a 
Dog  slightly  in  front  of  the  Optic  Commissure, 
showing  Ihe  anterior  part  of  the  'internal  capsule,' 
the  section  of  which  on  either  side  produces  Hemi- 
plegria.  (Oarville  and  Duret.)  S,  S,  intra-ventricular 
nuclei  of  the  Corpus  Striatum  ;  L,  extra-ventricular 
nucleus  of  the  same  ;  P,  peduncular  expansion  ■  'in- 
ternal capsule ')  ;  Ch,  Optic  Commissure ;  x,  section 
of  the  anterior  part  of  the  'internal  capsule,'  pro- 
ducing Hemiplegia  of  the  opposite  side  of  the  body. 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  567 

may  transmit  incitatioiis  capable  of  calling  into  action  the  closely 
united  double  groups  of  Spinal  Nerve- cells  which  minister  to  the 
bilateral  movements  of  the  trunk.  The  case  in  regard  to  the 
bilateral  movements  concerned  in  Speech  will  be  specially  referred 
to  in  a  subsequent  chapter. 

The  precise  mode  in  which  the  Corpus  Striatum  acts 
can  only  he  dimly  conjectured.  No  one  has  expressed 
the  kind  of  view  which  has  been  held  by  many,  better  or 
more  fully  than  Broadbent,  when  he  says*: — 

"  The  Corpus  Striatum  is  the  motor  ganglion  for  the  entire 
opposite  half  of  the  body.  It  translates  volitions  into  actions,  or 
puts  in  execution  the  commands  of  the  Intellect;  that  is,  it 
selects,  so  to  speak,  the  motor  nerve  nuclei  in  the  medulla  and  cord 
appropriate  for  the  performance  of  the  desired  action,  and  sends 
down  the  impulses  which  sets  them  in  motion.  These  impulses 
Are  transmitted  through  fibres,  and  the  fibres  must  start  from 
0^11  processes  in  the  corpus  striatum.  A  given  movemeQit,  therefore^ 
must  he  represented  in  the  Corpus  Stricdum  by  a  group  or  groups 
of  cells  giving  off  downward  processes,  which  become  fibres  of  the 
motor  tract  of  the  cord.  When  the  movement  is  simple,  or  when 
the  co-ordination  required  can  be  effected  by  the  cord  as  in  walking, 
the  cell  group  will  be  small,  and  the  descending  fibres  few.  When 
the  movement  is  complex  and  delicate,  and  guided  by  vision  or  by 
the  conscious  attention,  as  in  writing  or  drawing,  the  cell-groups  will 
be  large  and  definite,  and  the  descending  fibres  numerous.  There 
will  not  be  a  separate  group  of  cells  for  each  movement ;  but  the 
same  cells  may  be  differently  combined,  just  as  different  combina- 
tions of  carbon,  hydrogen,  oxygen,  and  nitrogen  form  the  basis  of 
all  organic  substances.  Words  which  require  for  their  utterance 
the  simultaneous  co-operation  of  muscles  of  the  chest,  larynx, 
tongue,  lips,  etc ,  and  the  exquisite  and  rapid  adjustment  of  their 
movements  concerned  in  phonation  and  articulation,  must  be  repre- 
sented in  the  Corpus  Striatum  by  very  large  groups  of  cells,  and 
nut  in  that  of  one  side  only  but  in  both." 

This  view  as  to  the  functions  of  the  Corpora  Striata  in 
regard   to    Voluntary   Movements    may  be  supplemented 

♦  *'  Brit.  Med.  Journal,"  April  1,  1870. 


568  WILL    AND 

by  the  same  writer's  notion  as  to  the  functions  of  the 
Cerebellum  in  the  j)roduction  of  such  Movements.  The 
respective  parts  which  he  is  inclined  to  assign  to  each  of 
these  oroans  will  thus  be  seen.     He  says  : — 

"The  Gerehellum  co-ordinates  movements  guided  by  vision,  or 
combines  the  general  movements  of  the  body  rendered  necessary  by 
sjJecial  actions  ordered  by  volition.  For  instance,  to  illustrate  the 
latter  function,  I  wish  to  strike  a  blow.  I  am  conscious  only  of 
the  desire  to  hit  the  object  and  hit  it  hard;  this  is  the  only  action 
realized  in  consciousness.  But  in  order  to  carry  out  the  intention, 
not  only  must  the  fist  be  clenched  and  the  arm  shot  out,  but  the 
feet  must  be  firmly  planted,  the  legs  made  rigid,  the  body  thrown 
forward,  the  chest  fixed;  and  this  is  what  is  done  for  me  by  the 

Cerebellum We  can  see  that  there  is  no  such  relation 

between  visual  impressions  as  between  these  and  tactile  imj)res- 
sions,  and  any  mechanism,  such  as  that  for  reflex  response  to  the 
latter,  is  impossible  as  regards  vision How  the  Cere- 
bellum is  acted  upon  by  the  Cerebrum  or  sensori-motor  ganglia, 
and  in  turn  acts  upon  the  cord,  we  do  not  yet  know." 

The  above  notions  entertained  by  Broadbent  in  regard 
to  the  functions  of  the  Cerebellum,  are,  in  part,  not  very 
different  from  what  have  been  expressed  in  Chap.  xxiv. 
There  are,  indeed,  good  grounds  for  believing  that  the 
Cerebellum  acts  in  some  way  at  the  instigation  of  the 
Cerebrum  in  the  production  of  Voluntary  Movements 
(see  p.  507) ;  and  in  these  cases,  as  already  explained,  the 
movements  are  mostly  guided  by  Vision.  On  the  other 
hand,  it  seems  obvious  that  the  Cerebellum  also  assists  in 
the  performance  of  '  automatic  '  Movements  of  the  highest 
or  most  general  order,  such  as  might  well  be  conceived 
to  fall  to  the  share  of  a  great  Motor  Ganglion  standing 
at  the  head  of,  but  in  intimate  relation  with,  all  other 
subordinate  motor  centres  in  the  Medulla  and  Cord. 
Being  concerned  as  it  is,  therefore,  both  with  new  and 
with  old  actions  it  has   an    essentially  double  function  ; 


Chap.  XXVL]  VOLUNTARY    MOVEMENTS.  669 

and  what  we  as  yet  know  of  its  anatomical  connections  i& 
harmonious  enough  with  this  view. 

In  what  precise  way  the  Cerebellum  acts  in  the  per- 
formance of  these  functions,  and  more  especially  those  in 
which  it  co-operates  with  the  Corpora  Striata  for  the  execu- 
tion of  Voluntary  Movements,  remains  at  present  wholly 
unknown.  Neither,  however,  can  we  do  more  than  con- 
jecture, when  we  try  to  realize  the  mode  in  which  the 
Corpora  Striata  themselves  react  under  Intellectual  Incita- 
tions  upon  the  motor  nuclei  of  the  Medulla  and  Cord, 
How  is  it  that  the  initiating  Idea,  the  Desire  for  a  related 
*  end,'  and  the  two-fold  Conception  of  the  necessary  Move- 
ments, as  co-operating  stimuli,  are  enabled  to  influence 
the  Corpora  Striata,  so  as  to  evoke  the  Movements  in 
question  ?  The  obscurity  prevailing  in  regard  to  this  prob  - 
lem  cannot  at  present  be  removed.  We  possess  no  real 
knowledge  on  the  subject,  and  me  rely  suppose  that  Intel- 
lect as  it  passes  over  into  actio  n — that  is  at  the  turning 
point  or  *  bend  of  the  stream '  — whilst  seeming  to  engender 
a  psychological  ghost  named  'Will/  operates  by  transmit- 
ting suitable  stimulations  to  the  Corpora  Striata  ;  and  that 
here  again,  perhaps  under  conjoint  stimulation  from  the 
Cerebellum,  in  some  manner  wholly  unknown,  other 
sequential  molecular  actions  are  roused,  as  a  result  of 
which  incitations  are  sent  to  and  through  motor  '  nerve- 
nuclei  '  in  the  M  eduUa  and  Cord,  appropriate  for  the  per- 
formance of  the  desired  Movements. 

But  another  final  set  of  questions  in  regard  to  the 
execution  of  Voluntary  Movements  now  remains  to  be 
considered.  We  have  pointed  out  the  track  taken  by 
cerebral  incitations  in  their  passage  downw^ards  from  the 
Corpora  Striata,  through  the  Cerebral  Peduncles,  Medulla, 
and  Cord,  and  thence  through  the  anterior  roots  of  Spinal 


570  WILL  ■  AND 

Nerves  to  the  requisite  groups  of  Muscles.  The  npper 
part  of  the  route  still  remains,  however,  to  he  specified. 
We  have  to  consider  whether  it  is  from  special  parts 
of  the  surface  of  the  Cerebral  Hemispheres — and  if  so, 
from  what  parts — the  before-mentioned  Intellectual  Incita- 
tions  (which  in  their  subjective  embodiment  are  commonly 
known  as  *  Will '  or  *  Volition ')  pass  downwards  to  the 
great  Motor  Ganglia — the  Corpora  Striata  ? 

Previous  to  the  experiments  of  Fritsch  and  Hitzig 
(1870)  and  of  Terrier  (1873)  it  had  been  generally  believed 
that  physical  irritations  of  the  surfaces  of  the  Cerebral 
Hemispheres  were  not  capable  of  evoking  any  definite 
Movements.  These  investigators,  however,  found  that 
some  definite  Movements  were  capable  of  being  produced 
by  electric  irritation  ;  and  that  though  the  Movements 
varied  in  character  they  were  more  or  less  similar  when 
the  same  limited  regions  of  the  surface  Grey  Matter  were, 
on  different  occasions,  stimulated  to  a  like  extent.  Fritsch 
and  Hitzig  originally  obtained  such  results  principally  by 
making  use  of  weak  '  voltaic  '  currents  ;  whilst  Ferrier'a 
subsequent  though  more  extensive  observations  were  made 
with  the  aid  of  weak  'induced'  currents.  The  Move- 
ments thus  produced  by  the  stimulation  of  certain  parts, 
were  found,  on  the  other  hand,  to  be  abolished  when  these 
same  parts  of  the  Cerebral  Cortex  had  been  destroyed — ■ 
that  is,  such  Movements  were  no  longer  capable  of  being 
performed  by  the  animal,  either  of  its  own  accord  or  as  a 
sequence  of  external  stimulation. 

Some  of  the  principal  facts  bearing  upon  this  question 
of  the  excitation  or  abolition  of  definite  Movements  as  a 
result  of  the  stimulation  or  destruction  of  definite  portions 
of  the  cortex  of  the  Brain  in  Monkeys*  may,  perhaps,  be 

*  The  Movements  of  these  animals  being  most  allied  to  those  oi 
Man,  and  their  Brains  being  also  most  similar  to  his,  it  will  ba 


Chap.  XXYI.l 


VOLUNTARY    MOVEMENTS. 


571 


most  briefly  set  fortli  by  quoting  Ferrier's  description  of 
some  observations  made  upon  an  animal,  certain  parts  of 
whose  Cerebrum  had  been  previously  submitted  to  electrical 
stimulation,  and  in  whom  tiie  initial  irritative  changes  were 
speedily  followed  by  destructive  morbid  processes,  involv- 
ing the  same  parts  of  the  Cerebral  Cortex. 

Ferrier  says  ('  Functions  of  tlie  Brain,'  p.  200; : — "  The  first  ex- 
periment I  have  to  record  is  instructive  as  showing  the  respective 
effects  of  irritation  and  destruction  of  the  convolutions  bounding 
the  fissure  of  Eolando.     The  right  hemisphere  of  a  monkey  had 


Fig.  181.— Lateral  View  of  the  Brain  of  a  Monkey,  showing  the  boundaries  of  the 
so-called  'motor area'  of  the  right  Cerebral  Hemisphere.  (Ferrier.)  c,  Fissure  of 
Rolando  ;  d,  the  parietal  lobule  ;  e,  the  ascending  frontal  convolution. 


been  exposed  and  subjected  to  experimentation  with  electrical  irri- 
tation. The  part  exposed  included  the  ascending  parietal,  ascend- 
ing frontal,  and  posterior  extremities  of  the  frontal  convolutions. 
The  animal  was  allowed  to  recover,  for  the  purpose  of  watching 
the  effects  of  exposure  of  the  brain.     Next  day  the  animal  was  found 

better  in  the  brief  space  which  we  can  here  devote  to  this  subject 
to  confine  our  observations  to  the  results  of  experiments  with 
these  particular  animals,  though  many  others  have  been  experi- 
mented upon  by  Dr.  Ferrier. 


572  WILL    AND 

perfectly  well.  Towards  the  close  of  the  day  following,  on  which 
there  were  signs  of  inflammatory  irritation  and  suppuration,  it 
began  to  suffer  from  chronic  spasms  of  the  left  angle  of  the  mouth 
and  left  arm,  which  recurred  repeatedly,  and  rapidly  assumed  an 
epileptiform  character,  affecting  the  whole  of  the  left  side  of  the 
body.  Next  day  left  hemiplegia  had  become  established,  the  angle 
of  the  mouth  drawn  to  the  right,  the  left  cheek-pouch  flaccid  and 
distended  with  food,  which  had  accumulated  outside  the  dental 
arch ;  there  being  almost  total  paralysis  of  the  left  arm,  and  partial 
paralysis  of  the  left  leg.  On  the  day  following  the  paralysis  of 
motion  was  complete  over  the  whole  of  the  left  side,  and  continued 
so  till  death,  nine  days  subsequently.  Tactile  sensation,  as  well  as 
sight,  hearing,  smell  and  taste  were  retained.  On  jpost-mortem 
examination  it  was  found  that  the  exposed  convolutions  were  com- 
pletely softened,  but  beyond  this  the  rest  of  the  hemisphere  and 

the  basal  ganglia  were  free  from  organic  injury In  this 

we  have  a  clear  case,  first,  of  vital  irritation  producing  precisely 
the  same  effects  as  the  electric  current,  and  then  destruction  by 
inflammatory  softening,  resulting  in  complete  paralysis  of  volun- 
tary motion  on  the  opposite  side  of  the  body,  without  affection  of 
sensation." 

The  important  observation  previously  made  by  Hngli- 
lings  Jackson  that  irritative  disease  of  the  corresponding 
region  of  the  Brain,  or  of  some  part  of  it,  in  the  human 
subject,  is  specially  apt  to  be  associated  with  a  liability  to 
unilateral  convulsions,  complete  or  partial,  of  the  opposite 
side  of  the  body,  was  thus  verified  so  far  as  it  could  be  by 
these  experimental  observations  upon  the  Monkey.  There 
is  reason  for  believing,  also,  that  destructive  disease  of 
the  Cerebral  Convolutions  in  this  region  may  lead,  in  the 
human  subject,  as  it  did  in  the  monkey,  to  a  condition 
of  complete  Hemiplegia.  In  each,  therefore,  both  in 
man  and  monkey,  irritation  of  certain  surface  regions  of 
one  of  the  Cerebral  Hemispheres  is  followed  by  choreiform 
twitchings  or  by  actual  Convulsions  on  the  opposite  side 
of  the  body,  whilst  destruction  of  the  same  parts  is  fol- 
lowed by  an  opposite  unilateral  Paralysis.     Irritation  and 


C.iAP.  XXVL]  VOLUNTARY    MOVEMENTS. 


573 


destruction  of  other  regions  of  the  surface  of  the  brain  in 
Monkeys,  were  followed  by  no  such  excitations  or  abolitions 
of  Movements. 

Details  cannot  here  be  given  as  to  the  effects  produced 
by  localized  irritations  or  destructions  of  limited  parts  of 
the  Convolutions  within  this  '  excitable  area.'  For  these 
the  reader  is  referred  to  Chap.  viii.  of  Ferrier's  work. 
The  principal  conclusions  at  which  he  has  arrived  may, 
however,  be  gathered  from  a  careful  study  of  Figs.  182, 183, 


Fio.  182.— Lateral  aspect  of  Monkey's  Brain,  showing  the  relative  positions  of  the 
fio-called  '  Motor  Centres '  in  the  left  Cerebral  Hemisphere.  (Ferrier.)  For  references 
see  Text,  and  also  Fig.  172. 

in  which,  as  a  result  of  his  investigations,  the  seats  of  the 
different  supposed  '  centres '  for  special  Movements  are 
indicated.     They  are  as  follows  : — 

(1.)  Centres  for  movements  of  the  opposite  leg  and  foot,  such  as 
are  concerned  in  locomotion — in  fostero-poirietal  lobule. 

(2,  3,  4.)  Centres  for  various  complex  movements  of  the  arms 
and  legs,  such  as  are  concerned  in  climbing,  swimming,  &c. — in 
the  convolutions  hounding  the  up'per  extremity  of  the  fissure  oj 
Rolando. 

(5.)  Centres  for  the  extension  forwards  of  the  arm  and  hand,  as 
ill  putting  forth  the  hand  to  touch  something  in  front — \i\  'posterior 
extremity  of  superior  frontal  convolation. 


574 


WILL    AND 


(6.)  Centre  for  the  movements  of  the  hand  and  forearm  in  which 
the  biceps  is  particnlarly  engaged  (viz.,  supination  of  the  hand  and 
flexion  of  the  forearm) — near  middle  of  ascendinrj  frontal,  oi^'posite 
'posterior  extreniitij  of  middle  frontal  convolution. 

(7  and  8.)  Centres  for  the  elevators  and  depressors  of  the  angle 
of  the  mouth — in  loiuer  end  of  ascending  frontal  convolution. 

(9  and  10),  included  together  in  one,  is  said  to  be  the  centre  for 
the  movements    of  the    lips  and  tongue,  as  in    articulation — in 

posterior  extremity  of  the 
lower  or  third  frorital  con- 
volution ('  Broca's  convolu- 
tion '). 

(11.)  Centre  for  retrac- 
tion of  angle  of  mouth — in 
supra  •  marginal  convolu- 
tion, near  loiuer  end  of 
ascending  itarietal. 

(12.)  Centre  for  lateral 
movements  of  the  head  and 
eyes,  with  elevation  of  the 
eyelids  and  dilatation  of 
the  pupil  (attitude  of 'atten- 
tion ') — in  'posterior  parts 
of  upper  and  middle  frontal 
convolutions. 

{a,  h,  c,  d.)  Centres  for 
movements  of  the  hand  and 
wrist  —  in  the  ascending 
parietal  convolution. 

The   relative  position  of 

showing  the  relative  positions  of  some  of  the    -^^jese  supposed  '  motor  cen- 
so-called  'Motor  Centres/  in  the  left  Cei^bral  ,  .     ^         ,^  ^^  ^^^^  ^f  ^^^^ 

Hemisphere.  (Ferrier.)  For  references  see  Text,     ^^'^^  ^ 

and  also  Fig.  172.  most  import  ant  alleged 'sen- 

sory  centres '  is  also  shown 
in  Fig.  182,  in  which  the  circles  13  and  13'  indicate  what  is  regarded 
•by  Ferrier  as  the  Visual  Centre  {in  the  supra-marginal  lohule  and 
the  angular  gyrus),  whilst  the  circles  14,  14  indicate  the  situation 
of  the  Auditory  Centre  {in  the  upper  temporal  convolution).  The 
centres  of  Touch,  Smell,  and  Taste  are,  as  we  have  previously 
inontioned  (pp.  53r,-r)40),  believed  to  be  located  in  convolutions  on 
the  inner  aspect  and  tip  of  the  Temporal  Lobe. 


Fig.  183. — Upper  aspect  of  Monkey's  Brain, 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  575 

As  an  example  of  the  kind  of  evidence  upon  which 
the  above-mentioned  localizations  in  regard  to  Special 
Movements  have  been  made,  one  of  Ferrier's  experimental 
observations  bearing  upon  this  point  may  be  quoted. 

"The  left  hemisphere  of  a  monkey  was  exposed  in  the  region 
of  the  ascending  frontal  convolution  sufficiently  to  display  the 
centre  of  bicipital  action  [fig.  182,  6j  or  supination  and  flexion  of 
the  forearm.  The  exact  spot  being  determined  by  the  application 
of  the  electrodes,  it  was  then  accurately  cauterised,  just  sufficiently 
to  destroy  the  cortical  grey  matter.  This  operation  immediately 
manifested  itself  in  paralysis  of  the  power  of  flexing  the  right  fore- 
arm. All  the  other  movements  of  the  limbs  were  retained,  but 
when  the  right  arm  was  placed  in  an  extended  position  the  animal 
was  utterly  powerless  to  flex  it,  and  the  limb  hung  in  a  state  of 

flaccid  extension  when    the    animal    was  lifted It   raised 

things  to  its  mouth  with  the  left  hand,  the  movements  of  the  leg 
were  intact,  there  was  no  facial  paralysis,  and  cutaneous  and  other 
forms  of  sensation  were  uuirapaired." 

Whether  or  not  the  various  details,  of  which  brief  indi- 
cations only  have  been  given,  are  destined  to  be  confirmed 
by  other  investigations,  it  seems  pretty  clear  (notwith- 
standing all  which  has  been  said  in  an  adverse  sense)  that 
experimental  observations  on  Monkeys,  as  well  as  clinico- 
pathological  data  gathered  from  the  study  of  the  effects  of 
disease  in  Man  alike  support  the  notion  that  certain  '  ex- 
citable regions '  of  the  Cerebral  Cortex  exist  in  each  Hemi- 
sphere, the  irritation  of  which  produces  Choreic  or  Convul- 
sive Movements  of  the  opposite  side  of  the  body,  and  the 
destruction  of  which  gives  rise  to  Paralysis  of  correspond- 
ing parts  of  the  body.  This  '  excitable  area  '  (figs.  172, 
182)  comprises  the  convolutions  which  border  on  or  are 
adjacent  to  the  '  fissure  of  Rolando,'  viz.,  the  ascending 
frontal  and  pari,  tal  convolutions,  the  postero-parietal 
lobule,  and  the  posterior  portions  of  the  three  tiers  of 
frontal  convolutions. 


576 


WILL   AND 


It  seems  safe  to  infer,  therefore,  that  these  portions  of 
the  Brain  are  in  some  way  related  to  the  production  of 
Movements.  The  evidence  pointing  to  such  a  conclusion 
is,  indeed,  precisely  similar  in  kind  to  that  which  leads  to 
the  inference  that  the  Corpora  Striata  are  concerned  with 
the  production  of  Movements. 

It  is  important,  moreover,  to  mention  that  Burdon 
Sanderson*  and  others  have  shown  that  the  same  special 
Movements  which  follow  irritation  of  special  limited 
portions  of  the  Cortex  may  also  he  evoked,  after  removal 
of  this  cortex,  on  stimulating  corresponding  regions  of  the 
subjacent  white  substance,  or  even  by  stimulating  portions 
of  the  surface  of  the  Corpora  Striata  themselves. 

It  may  therefore  be  regarded  as  fairly  well-established 
that  the  great  majority  of  stimuli  for  the  incitation  of 
Movements  of  the  Voluntary  and  Ideo-motor  types  pass 
off  from  the  regions  above  specified  of  the  parieto-frontal 
Grey  Matter ;  that  they  traverse  the  intervening  *  white 
substance '  to  reach  the  Corpus  Striatum  of  the  same  side, 
thence  to  pursue  the  course  already  indicated  through  the 
Cerebral  Peduncle,  the  half  of  the  Pons  and  Medulla,  to 
the  opposite  half  of  the  Spinal  Cord — from  whose  anterior 
horns  of  Grey  Matter  the  continuations  of  such  cerebral 
stimuli  23ass  away  by  the  *  anterior  roots'  and  *  motor 
nerves '  to  appropriate  groups  of  Muscles. 

So  that  if,  since  David  Hume's  time,  we  still  have 
not  learned,  in  any  full  sense  of  the  term,  "  the  means" 
by  which  "  the  motion  of  our  bodies  follows  upon  the 
command  of  our  Will,"  we  have  at  least  learned  something 
as  to  the  parts  chiefly  concerned,  and  thus  as  to  the  paths 
traversed  by  Volitional  Stimuli.  And  this  constitutes  an 
important  advance  in  our  knowledge  of  the  mode  of  action 
of  the  Brain  as  an  Organ  of  Mind. 

*  "  Proceed,  of  Eoyal  Society,"  June,  1874. 


Chap.  XXVI.]  VOLUNTARY    MOVEMENTS.  577 

The  next  question  that  arises  is  as  to  the  most  correct 
interpretation  of  the  newly  discovered  facts.  What  are 
the  functions  or  modes  of  activity  of  these  portions  of  the 
Cerebral  Cortex  whence  the  stimuli  emanate  which  are  to 
excite  special  Voluntaiy  Movements  ? 

Various  answers  have  been  given  in  reply  to  this  ques- 
tion. We  have  (a)  the  hypothesis  of  Ferrier,  that  the 
results  depend  upon  the  existence  of  '  motor  centres  '  for 
Volitional  Movements  in  the  cerebral  convolutions ;  (6)  the 
hypothesis  of  Schiff,  that  the  Movements  of  the  limbs 
resulting  from  stimulation  of  the  cortical  '  centres  '  are  of  a 
'  reflex '  nature,  and  that  the  affection  of  Motility  depen- 
dent upon  the  destruction  of  the  same  parts  is  essentially 
an  'ataxy'  resulting  from  loss  of  Tactile  Sensibility  ;  and 
(c)  the  hypothesis  of  Hitzig  and  Nothnao-el,  that  the  convo- 
lutional  areas  in  question  are  either  the  '  muscular  sense  ' 
centres,  or  parts  traversed  by  'muscular  sense'  impressions. 

{a,)  The  hypothesis  of  Ferrier  is  so  important  in  itself, 
has  been  so  ably  advocated  by  him,  and  already  numbers 
so  many  adherents,  as  to  make  it  desirable  that  we  should 
examine  his  views  pretty  closely. 

The  following  passages  have  seemed  to  the  writer  to 
embody  the  most  important  statements  and  views  adduced 
by  Ferrier  in  his  work  on  "  The  Functions  of  the 
Brain,"  in  support  of  his  position  that  '  motor  centres  ' 
exist  in  the  Cerebral  Convolutions.* 

(1.)  "  The  entire  removal  of  the  [cerebral]  hemispheres  operates 
differently  in  different  classes.  In  the  fish,  the  frog,  and  the 
pigeon  the  removal  of  the  hemispheres  exercises  little  or  no  appre- 
ciable effect  on  the  faculties  of  station  and  locomotion.  Under  the 
influence  of  stimulation  from  without,  these  animals  swim,  jump, 

*  The  passages  have  been  arranged  in  paragraphs  and  num- 
l>ered,  merely  for  the  purpose  of  facilitating  reference  to  the  various 
state ments  contained  therein. 


578  WILL    AND 

or  fly  with  as  mach  vigour  and  precision  as  before.  In  the  rabbit 
the  removal  of  the  hemispheres,  while  decidedly  impairing  the 
motility  of  the  fore  limbs,  does  not  quite  destroy  the  power  of 
station,  or  of  co-ordinated  progression  in  answer  to  external  stimuli. 

In  the    dog,  however,  the   removal   of   the    hemispheres 

exercises  a  much  more  marked  influence  on  these  powers,  rendering 
station  and  locomotion  absolutely  impossible"  (p.  207). 

(2.)  "  In  proportion,  however,  as  movements  at  first  requiring  voli- 
tional education  tend  to  become  organized  or  rendered  automatic, 
the  less  are  they  afl'ected  by  injury  to  the  cortical  centres.  Hence 
in  the  dog,  in  which  the  acquisition  of  the  control  of  the  limbs  is 
speedy,  the  destruction  of  the  cortical  centres  produces  a  much  less 
marked  effect;  the  movements  having  become  in  a  great  measure 
independent  of  these,  through  organization  in  the  subordinate 
centres  "  (p.  213).  "  In  the  optic  thalamus  and  the  corpus  stria- 
tum the  association  bfttween  certain  impressions  and  certain 
actions  becomes  so  mechanical  or  organized  that  if  we  were  to 
remove  from  the  dog  all  the  centres  above  the  basal  ganglia,  these 
would  of  themselves,  on  the  application  of  external  stimuli,  be 
sufiicient  to  carry  out  all  the  co-ordinated  movements  of  locomo- 
tion" (p.  214). 

(3.)  "The  more  the  control  of  the  limbs  depends  in  the  first 
instance,  and  continues  to  be  dependent  on  voluntary  acquisition, 
the  more  does  destruction  of  the  cortical  motor  centres  cause 
paralysis  of  movement.  Hence  in  man  and  the  monkey,  in  whom 
volition  is  predominant  and  automaticity  plays  only  a  subordinate 
part  in  the  motor  activities,  destruction  of  the  motor  centres  of  the 
cortex  causes  paralysis  of  a  very  marked  character  "  (p.  213). 

The  facts  cited  in  paragraph  (1)  are  important,  unques- 
tionably true,  and  in  part  well  known.  They  merely  tend 
to  show,  that  in  higher  forms  of  life  the  Cerebral  Hemi- 
spheres with  the  Corpora  Striata  gradually  take  on  some 
of  the  functions  which  in  lower  animals  have  been  dis- 
charged through  the  intermediation  of  Medullary  and 
Spinal  Centres.  The  Cerebral  Hemispheres  in  higher 
animals  come  to  exercise,  therefore,  a  larger  proportionate 
share  of  influence  in  the  execution  even  of  the  common 
movements  needed  for  Locomotion. 


Clip.  XXVI.]  VOLUNTARY    MOVEMENTS.  679 

The  statements  made  in  paragraphs  (2)  and  (3),  though 
they  may  be  perfectly  true,  lend  no  special  support  to  the 
doctrine  of  Hughlings  Jackson  and  of  Ferrier.  They  are 
equally  or  even  more  in  accord  with  the  views  expressed  in 
this  chapter.  The  damage  or  removal  of  parts  of  the  Brain 
concerned  to  a  large  extent  with  the  Intellectual  direction 
of  Movements,  of  parts  which  are  accustomed  in  the  most 
direct  manner  to  call  into  activity  the  Corpora  Striata  (the 
great  motor  ganglia  of  the  Hemispheres),  would  necessarily 
interfere  with  the  performance  of  each  of  such  Movements 
precisely  in  proportion  to  the  need  for  intellectual  guidance 
in  order  to  ensure  its  execution.  The  destruction  of  such 
cortical  areas,  in  fact,  puts  the  Corpora  Striata  themselves 
out  of  court,  for  the  execution  of  all  Movements  except 
those  which  are  at  once  simple  and  '  automatic'  Hence 
it  is  that  the  facts  above  cited  lend  no  exclusive  support 
whatever  to  the  notion  that  '  motor  centres  '  exist  in  the 
Cerebral  Convolutions. 

In  the  following  paragraphs  Ferrier  sets  forth  certain 
developments  or  corollaries  from  his  doctrine. 

(4.)  "The  dog  from  which  the  cortical  motor  centres  alone  have 
been  removed  is,  however,  in  a  very  different  position.  lb  retains 
its  sensory  centres,  and  is  a  conscious  sentient  animal,  and  is 
capable  of  ideation  and  emotion.  It  is  not  merely  a  mechanism, 
the  activit}'-  of  which  is  dependent  purely  on  external  stimulation, 
but  has  within  itself  the  springs  of  action  in  the  mediate  form  of 
revived  or  ideal  impressions,  and  is  thus  capable  of  spontaneous 
action.  As,  however,  the  revived  impressions  occupy  the  same 
place,  or  coincide  with  the  physiological  activity  of  the  same  parts 
as  are  engaged  in  the  consciousness  of  present  impressions,  the 
revived  impressions  can  throw  the  automatic  apparatus  of  move- 
ment into  action  just  as  well  as  immediate  or  present  impressions" 
(p.  214) 

(5.)  "  In  the  dog  deprived  of  its  cortical  centres  the  path  from 
impression  to  action  is  not,  as  in  the  ordinary  course  of  volition, 
through  the  cortical  motor  centres  to  the   Corpus  Striatum,  and 


580  WILL    AND 

thence  downwards  to  the  motor  nuclei    and    motor    nerves,  but 
through  the  basal  ganglia  directly  "  (p.  215). 

The  suggestion  here  made  that  the  *  way  out '  from  the 
cerebral  cortex  is  different  in  the  case  of  Voluntary  from 
what  it  is  in  Ideo-motor  Movements  has  never  been 
proved,  and  is  directly  contra-indicated  by  all  that  we 
know  concerning  Speech  and  its  defects.  The  few  difficult 
phenomena  to  be  explained  in  reference  to  Emotion  as  an 
instigator,  in  cases  where  Speech  is  otherwise  lost,  does  not 
warrant  the  statement  above  made  that  in  Ideo-motor  and 
Emotional  Acts  generally  the  *  way  out '  is  *'  through  the 
basal  ganglia  directly."  This  statement  is,  to  say  the 
least,  hypothetical  and  vague  ;  nor  is  it  correct  to  say  that 
revived  impressions  *'  can  throw  the  automatic  apparatus 
of  movement  into  action  just  as  well  as  immediate  or 
present  impressions."  They  are  proverbially  weaker,  and, 
therefore,  less  potent  inciters  of  Movement.  And,  unless 
the  supposition  that  there  is  a  distinct  way  out  for  Ideo- 
motor  and.  Emotional  Stimuli  is  better  founded  than  it 
appears  to  be,  they  could  not  act  at  all  in  the  case  sup- 
posed. Dr.  Ferrier  must  either  make  all  these  points 
much  clearer,  or  else  he  must  give  up  the  attempt  to 
explain  a  fact  so  damaging  to  his  hypothesis  as  that  of 
the  recovery  of  motor  power  in  the  dog  after  the  removal 
of  what  he  regards  as  its  "voluntary  motor  centres." 
The  close  relationship  existing  between  the  Voluntary  and 
Ideo-motor  modes  of  stimulation  to  Movement,  does  not 
seem  to  have  been  adequately  appreciated  by  Ferrier. 
Again,  he  says  : — 

(6.)  **  A  dog,  therefore,  deprived  of  its  cortical  motor  centres  may 
yet  be  capable  of  spontaneous  action  and  co-ordinated  locomotion, 
under  the  influence  of  present  or  past  impressions,  or  of  emotional 
states.  Only  such  mv")vements,  however,  will  be  excited  as  have 
been  automatically  organized  in  the  corpora  striata.     The  move- 


Chap.  XXVL]  VOLUNTARY    MOVEMENTS.  581 

ments  of  locomotion  having  become  automatic  may  thus  be  easily 
effected,  and  the  dog  may  be  able  to  walk  with  as  much  apparent 
steadiness  as  before." 

(7.)  "The  Corpus  Striatum  is  the  centre  in  which  movements 
primarily  dependent  on  Volition  proper  tend  to  become  organized  '* 
(p.  214). 

(8.)  "  It  may  be  confidently  asserted,  and  perhaps  it  may  be  one 
day  resolved  by  experiment,  that  any  special  tricks  of  movement 
which  a  dog  may  have  learnt  would  be  as  effectually  paralyzed  by 
removal  of  the  cortical  centres  as  the  varied  and  complex  move- 
ments of  the  arm  and  hand  of  the  monkey  by  the  same  lesion.* 
Such  forms  of  activity  "  as  are  not  habitual,  and  have  not  becomo 
automatic,  would  be  rendered  impossible"  (p.  215). 

There  are  good  reasons  for  believing,  that  no  such  defi- 
nite distinctions  exist  between  Voluntary  and  Automatic 
Movements  as  are  postulated  by  Ferrier.  It  seems  not 
only  unnecessary  but  altogether  unphilosophical  to  look 
for  the  nervous  '  organizations '  pertaining  to  Voluntary 
Movements  in  centres  altogether  apart  from  those  in  which 
Automatic  Movements  are  *  organized.'  The  Voluntary 
Movements  of  one  set  of  generations  tend  to  become  the 
Automatic  Movements  of  remote  progeny  in  subsequent 
generations.  In  the  intervening  periods  less  and  less  will 
depend  upon  higher  Cerebral  Influence — or,  in  other  words, 
upon  Intellectual  guidance. 

Ferrier*  seems  to  us  to  start  with  a  fundamental  mis- 
conception in  supposing,  in  reference  to  Cortical  Centres, 
that  those  "  immediately  concerned  in  effecting  volitional 
movements"  are  "  as  such  truly  motor  "  ;  or  that  because 
Voluntary  Movements  are  paralyzed  after  the  destruction 
of  these  parts,  we  have  in  this  fact  evidence  to  show  that 
they  are  "  motor  centres."  If  '  Will '  or  Volitional  Stimuli 
are  not  altogether  independent  and  self-begotten  entities — ■ 
and  this  Dr.  Ferrier  is  far  from  believing — they  can  only 

*  Loc.  cit.  p.  2C0, 


682  WILL    AND 

be  regarded  as  taking  origin  from  the  organic  seats  of 
Perceptive  and  Intellectual  Actions.  As  Spinoza  pointed 
out  over  two  centuries  ago,  "  The  Will  and  the  Intelligence 
are  one  and  the  same  thing  " — viev/ed,  however,  from  a 
slightly  different  aspect. 

(b.)  According  to  Schiff  and  others,  the  parts  deemed 

*  motor  centres '  by  Ferriei  are  rathei  to  be  regarded  as 
centres  of  Touch.  The  movements  of  the  limbs  which 
result  from  stimulation  of  these  centres,  they  consider  as 
of  a  '  reflex '  nature  ;  whilst  the  affection  of  Motility  re- 
sulting from  their  destruction  is  supposed   to  be   of  an 

*  ataxic '  order  and  occasioned  by  loss  of  Tactile  Sensi- 
bility. 

Against  this  explanation,  there  is  the  fact  that  injury  to 
such  regions  of  the  surface  of  the  Brain  do  not  appear  to 
cause,  either  in  the  low^er  animals  or  in  Man,  any  distinct 
impairment  of  the  sense  of  Touch  ;  neither  does  it  appear 
to  be  true,  as  was  formerly  believed,  that  mere  loss  of  Tactile 
Sensibility,  even  if  it  did  exist,  would  of  itself  cause 
either  ataxic  or  paralytic  symptoms.  The  evidence  fur- 
nished by  persons  suffering  from  complete  Hemi-amesthesia, 
as  well  as  that  occasionally  supplied  by  persons  suffering 
from  some  forms  of  *  locomotor  ataxy,'  seems  to  show  that 
loss  of  Tactile  Sensibility  alone  causes  no  api3reciable 
interference  with  the  Movements  of  the  affected  parts. 
This  is  the  opinion  of  Charcot,  of  Broadbent,  and  others, 
and  it  is  entirely  confirmed  by  the  writer's  own  examina- 
tion of  the  celebrated  Hcmi-an?esthetics  of  '  la  Salpetriere  * 
when  visiting  Prof.  Charcot's  wards  last  autumn.*  The 
evidence  that  formerly  seemed  to  support  the  opposite 
opinion,  and  with  which  Ferrier  appears  to  have  been  still 

*  For  an  a'jcount  of  these  patients  see  "  Bfit.  MeJ.  Journal," 
Oct.  12, 1878.     See  also  Ziemsscu's  "  Cyclopajdia,''  vol.  xiii.  p.  88. 


Chap.  XXVI.  VOLUNTARY    MOVEMENTS.  583 

impressed  at  the  time  of  the  publication  of  his  work,  is 
unquestionably  defective,  and  stands  in  need  of  revision. 

(c.)  According  to  Hitzig,  and  also  to  Nothnagel,  tho 
affection  of  Motility  resulting  from  the  destruction  of  the 
cortical  regions  in  question  is  due  to  a  paralysis  of  the 
animal's  '  muscular  sense.'  Nothnagel  thinks  the  fact  of 
the  recovery  of  Movement  after  a  time  in  dogs  proves  that 
the  centre  of  the  '  muscular  sense '  is  not  itself  destroyed, 
but  that  the  destruction  of  the  particular  regions  of  the 
cortex  has  sufficed  to  interrupt,  for  a  time,  and  not  far 
from  their  termini,  the  paths  for  such  ingoing  impressions. 
Hitzig,  on  the  other  hand,  seems  more  inclined  to  believe 
that  the  centre  itself  ('  End-station  ')  for  impressions  of  the 

*  muscular  sense  '  or  '  muscle-consciousness  '  is  destroyed 
by  the  experimental  lesions.  Or,  if  this  be  not  the  case, 
he,  like  Nothnagel,  is  disposed  to  believe  that  the  afferent 
path  from  muscle  to  *  mind  '  is  in  some  way  interrupted. 
Both  these  investigators,  in  further  support  of  their 
notion,  say  that  the  condition  of  the  animal,  in  regard 
to  Motility,  is  somewhat  similar  to  that  of  a  Man  who  is 
suffering  from  the  disease  known  as  *  locomotor  ataxy.' 

Ferrier,  in  opposition  to  this  view,  contends  that  "loss 
of  the  muscular  sense  without  any  affection  of  the  other 
forms  of  common  or  tactile  sensibility  is  a  condition  the 
existence  of  which  is  purely  hypothetical."  He  further 
considers  that  no  investigations  bearing  upon  the  subject 
have  furnished  the  slightest  evidence  of  impairment  or 
loss  of  Touch  or  Common  Sensibility  when  his   so-called 

*  motor  centres  '  have  been  destroyed  :  hence  he  infers  that 
the  '  muscular  sense  '  has  also  remained  unimpaired  {see 
p.  69).  The  affection  of  motility  met  with  after  destruction 
of  the  so-called  '  motor  centres,'  he  says, — "  only  resembles 
ataxia  in  the  case  of  the  cat,  dog,  &c. ;  but  in   man  and 


584  WILL    AND 

the  monkey  the  resemblance  fails,  for  in  these  there  13 
complete  motor  paralysis,  with  distinct  retention  of  the 
pristine  sensibility  to  the  various  forms  of  cutaneous 
stimulations.  The  argument  from  mere  resemblance  is 
thus  seen  to  fail  when  a  wider  comparison  of  instances  is 
made.  But,  further,  it  has  been  shown  that  the  condition 
which  may  with  truth  be  described  as  loss  of  muscular 
sense  or  of  muscle-consciousness  is  dependent  on  lesion 
of  a  totally  different  part  of  the  brain,  viz.,  the  hippocam- 
pal  region,  or  centre  of  tactile  consciousness."* 

These  objections  of  Ferrier  to  the  views  of  Nothnagel 
and  Hitzig  do  not  seem  to  us  to  have  nearly  as  much 
cogency  as  he  supposes.  Our  knowledge  in  regard  to 
several  of  the  points  touched  upon  by  him  is  far  from 
complete,  but  the  evidence  at  present  in  our  possession  may 
be  interpreted  quite  differently.  Thus,  the  observations  of 
Landry,  as  well  as  the  case  of  Demaux  f  when  contrasted 
with  that  of  ordinary  hemi-an^esthetic  patients,  make  it 
probable  that  unconscious  *  muscular  sense '  impressions, 
in  the  restricted  sense  of  that  term,  have  a  distinct  exist- 
ence, and  probably  a  cerebral  '  locus  '  of  their  own,  quite 
apart  from  Tactile  Impressions,  whatever  may  be  the  region 
of  the  Cortex  to  which  the  latter  are  specially  distributed. 
The  paths  for  these  two  classes  of  Impressions,  viz.,  those 
from  Muscles  and  those  from  Skin,  seem  to  be  topo- 
graphically distinct  in  the  Spinal  Cord ;  they  are  probably 
more  or  less  contiguous  in  the  Cerebral  Peduncles  ;  whilst 
they  may  subsequently  diverge  again  and  go  to  different, 
though  functionally  related.  Cerebral  Convolutions,  rather 
than  to  the  same  cerebral  region  as  Ferrier  seems  to  sup- 
pose {see  p.  544). 

The  Cerebral  Cortex  is,  in  our  view,  to  be  regarded  as  a 
continuous  aggregation  of  interlaced '  centres,'  towards  which 
*  Loc.  cit.  p,  218.  t  See  Appendix,  p.  700. 


CriAP.  XXVT.]  VOLUNTARY    MOVEMENTS.  585 

ingoing  Impressions  of  all  kinds  converge  from  various 
parts  of  the  body  :  here  they  come  into  relation  with  one 
another  in  various  ways,  and  conjointly  give  rise  to  nerve 
actions,  which  have  for  their  subjective  correlatives  all  the 
Sensations  and  Perceptions,  all  the  Intellectual,  and  all 
the  Emotional  Processes  which  the  individual  is  capable  of 
experiencing.     From  these  terminal  and  complexly  related 

*  end-stations  '  for  ingoing  currents,  and  from  certain 
annexes  in  connection  therewith,  outgoing  currents  issue, 
which  rouse  in  definite  ways  the  activity  of  the  highest 

*  motor  centres  '  (the  Corpora  Striata  and  Cerebellum), 
and  through  them  evoke  the  properly  adjusted  activity  of 
lower  motor  combinations,  so  as  to  give  rise  to  any  Move- 
ments that  are  '  desired,'  or  which  are  accustomed  to 
appear  in  response  to  particular  Sensations  or  Ideas. 

The  plan  on  which  Nerve  Centres  generally  are  con- 
structed, of  whatsoever  grade,  makes  it  essential  that  the 
stimulus  which  awakens  the  activity  of  a  '  motor  '  ganglion 
or  centre  shall  come  to  it  through  connecting  fibres  from 
a  '  sensory  '  ganglion,  centre,  or  knot  of  cells — that  is, 
from  cells  which  stand  in  immediate  relation  with  ingoing 
fibres  (see  p.  26). 

If  we  turn  to  the  very  simple  nervous  system  of  a  Slug 
(fig.  27)  we  find  two  upper  Sensory  Ganglia,  connected  by 
distinct '  commissures  '  with  two  conjoined  Motor  Ganglia. 
It  can  scarcely  be  doubted  that  stimuli  (as  sequences  of 
the  nervous  processes  concerned  with  Sensations)  are  accus- 
tomed to  pass  from  these  Sensory  Ganglia  along  the  '  com- 
missural '  fibres  uniting  them  with  the  Motor  Ganglia,  and 
that,  in  accordance  with  their  different  origins  or  starting- 
points,  these  stimuli  may  cause  the  latter  Ganglia  to 
evoke  distinctive  muscular  contractions  in  various  parts  of 
the  body.  Could  we  galvanize  separately  the  several  sensory 
ends  of  these  '  internuncial '  fibres  we  should  doubtless 


586  WILL    AND 

evoke  similar  Movements.  But  would  such  facts  entitle 
us  to  infer  that  these  Sensory  Ganglia  contain  *  motor' 
Centres  ?  Assuredly  not :  no  more  than  we  should 
be  entitled  to  call  the  *  sensory  cells  '  on  the  ingoing  side 
of  a  simple  mechanism  for  some  Keflex  Action  '  motor 
cells,'  simply  because  a  stimulus  issues  from  them  which 
ultimately  evokes  the  Movement — that  is,  after  it  has 
passed  through  other  nerve  elements  which,  by  common 
consent,  are  regarded  as  '  motor  cells.' 

The  nervous  fibres  that  ext<3nd  from  the  Cerebral 
Cortex,  in  higher  animals  and  in  Man,  down  to  the 
Corpora  Striata  are,  in  their  nature,  strictly  comparable 
with  the  fibres  connecting  the  '  sensory  '  and  the  '  motor' 
Cells  in  an  ordinary  nervous  mechanism  for  Reflex 
Action.  Such  currents  from  '  sensory  '  cells  may  pass  in 
the  same  horizontal  plane,  they  may  have  to  ascend,  or, 
as  frequently  happens,  they  may  descend  to  '  motor '  cells 
situated  at  a  lower  level.* 

The  Corpora  Striata,  conjointly  with  the  Cerebellum, 
are  doubtless  specially  called  into  activity  by  the  Cere- 
bral Cortex,  in  ways  which  are  most  important  though 
they  cannot   be  precisely  defined.     These  organs,  as  we 

*  On  account  of  the  variability  of  this  relation,  therefore,  such 
nerve  fibres  cannot  be  considered  to  be  invariably  in  relation  either 
with  'ingoing'  or  with  'outgoing'  currents.  We  may  distinguish 
them  by  the  name  of  '  iuternuncial  fibres,'  with  the  understanding 
that  in  different  parts  of  the  Nervous  System  currents  are  trans- 
mitted along  them  in  an  ascending,  a  horizontal,  or  in  a  descending 
direction.  Still,  as  the  stimuli  emanating  from  the  Sensory 
Centres  and  their  annexes  in  the  Cerebral  Cortex,  at  once  take  a 
downward  direction  to  the  Corpora  Striata,  it  will  be  most  con- 
venient in  this  case,  to  speak  of  the  origin  of  *  outgoing '  currents 
as  being  from  the  Cerebral  Cortex  itself,  and  to  regard  certain  of 
its  Centres  as  occupying  what  has  been  aptly  termed  the  '  bend  of 
the  stream  ' — that  is  the  regions  where  *  ingoing  '  currents  end  or 
give  place  to  '  outgoing'  currents. 


CiiAP.  XXVI.]  VOLUNTARY    MOVEMENTS.  587 

contend,  are  the  great  motor  ganglia  through  which  cortical 
stimuli  resulting  from  so-called  '  Volitional '  or  Intellec- 
tual guidance  operate.  If,  indeed,  what  has  been  set 
forth  in  this  chaptei  gives  anything  like  a  true  account  of 
the  relations  existing  between  Voluntary  and  Automatic 
Movements,  not  another  word  need  here  be  said  against 
the  general  point  of  view  upon  which  Hughlings  Jackson 
and  Ferrier  rest  their  hypothesis  as  to  the  existence  of 
'motor  centres'  in  the  Cerebral  Cortex,  nor  against  the 
view  that  the  mechanisms  for  Voluntary  Movements  are 
*  organized  '  in  regions  altogether  apart  from  those  con- 
cerned with  the  execution  of  Automatic  Movements. 

What  has  been  said  in  the  earlier  parts  of  this  chapter 
in  reference  to  the  origin  and  nature  of  '  Volitional ' 
stimuli,  together  with  what  has  been  stated  above,  make 
it  possible  to  explain  the  results  of  irritation  and  de- 
struction of  certain  fronto-parietal  areas  of  Grey  Matter 
and  of  the  white  matter  intervening  between  them  and 
the  Corpora  Striata,  without  in  the  least  countenancing 
the  supposition  that  '  motor  centres  '  exist  in  the  Cerebral 
Convolutions.* 

The  Centres  in  question  are  rather  'sensory'  in  nature, 
and  are  probably  intimately  concerned  with  certain  groups 
of  Kinoesthetic  Impressions — whatever  other  functions 
they  may  subserve,  or  with  whatever  other  centres  they 
may   be   in   intimate   relation.     We   have,    indeed,   seen 

*  V^^e  have  here,  in  fact,  to  do  with  a  misconception  very  simi- 
lar in  kir.d  to  that  which  jDreviously  led  Foville  and  others  to 
regard  the  Cerebellum  as  a  Sensory  Organ  (p.  604)  simply  because 
'  internuncial  fibres  '  enter  it  from  various  sensory  nuclei  or  ganglia. 
To  argue  that  groups  of  cells  have  motor  functions,  merely  because 
stimuli  issuing  from  them  evoke  movements  when  they  impinge 
upon  motor  ganglia,  is  quite  on  a  par  with  the  argument  that  an 
organ  has  sensory  functions  because  fibres  come  to  it  from  sensory 
cells. 


5S8     WILL  AND  VOLUNTARY  MOVEMENTS. 

reason  for  believing  that  the  Kinsesthetic  must  be  in  the 
closest  functional  relationship  both  with  the  Visual  and 
with  the  Auditory  Centres.  From  one  or  more  (but  per- 
haps more  especially  from  the  first)  of  these  inter-related 
Perceptive  Centres  or  their  annexes,  *  internuncial  fibres' 
issue,  by  which  they  are  brought  into  functional  relations 
wdth  the  great  underlying  motor  ganglia — the  Corpora 
Striata. 

Stimulation  of  certain  sets  of  such  '  internuncial  fibres ' 
should  produce  special  Choreic  or  Convulsive  Movements ; 
destruction  of  them  should  produce  Paralysis  ;  and,  look- 
ing to  the  direction  in  which  they  transmit  their  stimuli, 
analogy  would  lead  us  to  infer  that  the  severance  of 
their  connections  with  cortical  nerve-cells  might  lead  to 
small  bands  or  tracts  of  *  descending  degenerations  '  be- 
tween the  seats  of  such  severance  and  the  corresponding 
Corpus  Striatum — yet  these  are  the  results  the  occurrence 
of  which  is  so  confidently  relied  on  by  some  in  support 
of  the  *  motor  *  functions  of  such  portions  of  the  Cerebral 
Cortex. 


CHAPTEK   XXVII. 

CEREBRAL   MENTAL    SUBSTRATA. 

After  tlie  first  *  Sensation '  nothing  strictly  answering  to 
this  term  exists.  We  only  consciously  realize  any  impres- 
sion, as  of  such  and  such  a  nature,  hy  automatic  com- 
parison of  it  with  other  impressions  which  have  gone 
before  it.  A  simple  '  Sensation '  can,  in  fact,  scarcely 
exist  in  consciousness,  nor  can  it  be  imagined  by  us  in 
our  present  phase  of  mental  evolution.  Our  so-called. 
'  Sensations  '  are  really  Perceptions.  In  one  and  the  same 
act  or  state  each  of  them  embodies  Feeling  and  Intelli- 
gence in  indissoluble  connection. 

A  seat  of  '  simple  '  or  '  brute  '  Sensation  is,  therefore, 
not  to  be  looked  for.  The  seats  of  conscious  sensibility  in 
the  only  intelligible  phase  in  which  such  states  can  exist 
for  us  are  centres  for  Perception*. 

As  the  act  of  Perception  involves  the  automatic  com- 
parison of  present  impressions  with  revived  past  impres- 
sions of  the  same  kind,  as  well  as  of  some  or  all  other 
kinds  of  impressions  capable  of  being  yielded  by  the 
Object  perceived,  it  happens  that  even  in  the  simplest  so- 
called  '  Sensation  '  the  conjoint  activity  is  necessitated  of 
no  one  limited  tract  of  convolutional  grey  matter — but 
rather  of  widely  extended  cell-and-fibre  mechanisms 
corresponding,  it  may  be,  with  many  more  or  less  diffused 
and  complexly  related  Perceptive  Centres  (p.  522). 

Seeing  that  each  Perceptive  Centre  forms  the  basis  or 
starting   point   of   different   processes   of   Ideation,   and, 
*  See  pp.  176,  524,  and  "  Nature,"  Jan.  20, 1870,  p.  309. 
26 


5C0       CEREBRAL  MENTAL  SUBSTRATA. 

therefore,  of  Thought,  and  that  the  several  centres  must 
have  the  same  kind  of  relation  to  Emotion,  we  may  find 
therein  additional  reason  for  the  belief  that  the  different 
Perceptive  Centres  are  diffuse  in  seat,  and  that  widely 
separated  parts  of  the  Cerebral  Hemispheres  are  probably 
knitted  together  for  simultaneous  action  even  in  the 
simplest  sensory  Perception — containing,  as  this  process 
does,  the  germs  of  Thought  and  Emotion,  to  say  nothing 
of  '  Volition  '.*  And  although  these  diffuse,  but  func- 
tionally unified,  nervous  networks  may  differ  much  from 
ordinary  '  Centres '  (owing  to  their  assumed  lack  of  topo- 
graphical distinctness  and  exclusiveness),  it  is  still  con- 
venient to  be  able  to  refer  to  such  networks  as  *  Centres.' 

But  in  addition  to  the  complex  perceptive  mechanisms 
in  relation  with  the  'five  senses,'  there  are  also  other  Cere- 
bral Centres  for  ingoing  impressions,  some  of  which  are, 
when  in  action,  habitually  attended  by  more  or  less  of 
Consciousness,  whilst  others  are  as  constantly  devoid  of 
any  such  accompaniment.  Yet  all  these  '  Centres  ' — quite 
irrespective  of  the  degree  of  vividness  of  the  subjective 
accompaniments  dependent  upon  their  activity — are  pro- 
bably situated  in  some  portions  of  the  Cerebral  Cortex.  ■)■ 

*  See  Dr.  Lombard,  "On  the  effect  of  Intellectual  and  Emo- 
tional Activity  on  the  Temperature  of  the  Head,"  in  "  Proceed,  of 
Royal  Society,"  1878,  p.  462. 

f  Among  these  a  '  sense  of  Space '  Centre  ought,  perhaps,  to  be 
include*.!,  the  activity  of  which  would,  however,  be  of  less  import- 
ance for  Man  than  for  many  of  the  lower  animals  (pp.  214-219). 
The  instinctive  and  untaught  migrations  of  young  Birds  may  depend 
much  upon  the  automatic  activity  of  this  Centre,  and  are  pb.enoniena 
of  the  same  order  as  the  instinctive  fear  of  the  young  Turkey  on 
hearing  the  cry  of  the  Hawk  (p.  189),  or  the  instinctive  apprecia- 
tion of  food  and  distance  which  enables  the  young  Chick  to  snap  at 
and  capture  a  Bee  (p.  188).  In  all  these  cases  we  have  to  do  with 
automatic  Perceptions,  as  well  as  with  Automatic  Movements. 


CflAP.  XX VII.]    CEREBRAL  MENTAL  SUBSTRATA.  591 

There  are,  in  the  first  place,  termini  for  the  important 
class  of  Yisceral  Impressions  which,  so  far  as  they  are 
connected  with  the  animal's  '  life  of  relation,'  are  divisible 
into  two  main  categories — the  Alimentary  and  the  Grenital. 
The  parts  of  the  Visceral  Centre  appertaining  to  these 
sets  of  impressions  are  the  cerebral  foci  in  relation  with 
two  all-powerful  *  appetites'.  They  must,  each  of  them,  be 
in  intimate  connection  with  the  special  Perceptive  Centres, 
whose  activity  is  conjointly  roused  during  the  times  of 
recurrence  and  active  manifestation  of  the  various  Instincts 
of  lower  animals,  as  well  as  during  the  various  phases  of 
human  passion  and  action  which  are  immediately  or  re- 
motely connected  with  such  Yisceral  Impressions. 

Differing  altogether  from  the  foregoing  Impressions, 
both  'special'  and  'visceral'  (though  their  related  physical 
mechanisms  may  be  inextricably  intermixed),  we  have 
another  great  class  of  Impressions — viz.,  those  of  Kin- 
£Osthesis.  Here  we  are  not  concerned,  except  indirectly, 
with  impressions  made  upon  the  external  or  interual 
surfaces  of  the  Organism.  Such  impressions  evoke  Move- 
ments, and  these  in  their  turn  occasion  various  ingoing  im- 
pressions. Some  of  these  latter  Kinaesthetic  Impressions 
(such  as  those  occasioned  by  the  contractions  of  the  Heart 
and  of  the  Alimentary  Canal)  give  rise  in  the  healthy 
human  being  to  no  recognizable  phase  of  Consciousness : 
it  is  even  doubtful  whether  some  of  them  ever  reach 
the  Cerebrum.  Other  of  these  impressions,  however — 
especially  in  case*s  where  Muscles  are  called  into  play 
voluntarily  in  unaccustomed  actions,  and  where  the  Move- 
ments produced  affect  large  Joints  or  tracts  of  Skin — 
give  rise  to  more  or  less  distinct  states  of  Consciousness, 
and  thus  place  it  beyond  all  reasonable  doubt  that  such 
impressions  reach  the  Kinaesthetic  Centres  in  the  curtex 
of  the  Hemispheres. 


592       CKRKBRAL  MENTAL  SUBSTKATA. 

It  is  of  importance  to  remember,  concerning  tins  last 
Sense-endowment,  that  part  of  its  impressions  are  dis- 
tinctly Tactile  in  nature,  and  as  such  are  probably  reahz- 
able,  or  have  their  organic  seats,  in  portions  of  the 
Tactile  Centre ;  and  that  those  of  them  which  are  least 
attended  by  Consciousness  are  probably  the  impressions 
emanating  from  the  Muscles  themselves.  These  last 
components  of  the  many-sided  Kinesthetic  Sense  corre- 
spond, in  the  main,  with  what  has  been  erroneously 
termed  '  muscular  consciousness,'  or  with  the  '  muscular 
sense  '  in  the  most  limited  acceptation  in  which  this  latter 
term  has  been  used. 

The  occurrence  of  Movement  is  for  the  Kinaesthetic 
Sense,  what  the  presentation  of  an  object  is  to  the 
Visual  Sense ;  and  the  inability  to  cognize  the  impres- 
sions occasioned  by  Movement  (either  those  that  are 
conscious,  those  that  are  unconscious,  or  both)  which  is 
sometimes  produced  by  certain  morbid  conditions,  is  a 
defect  of  the   Kinaesthetic   Sense  altogether  analogous  to 

*  blindness'  in  relation  to  the  Sense  of  Vision.  To  speak 
therefore,  as  Ferrier  does,*  of  this  sequence  of  Movement 
and  the  Sensations  thereby  induced,  as  a  "  sensori-motor 
association,"  is  altogether  to  miss  and  invert  the  real 
significance  of  the  phenomxcna  to  which  he  refers. 

The  impressions  coming  from  every  one  of  the  '  special ' 
Sense  Organs  are,  in  part,  dependent  for  their  various 
combinations  upon  the  Movements  of  such  organs,  and 
for  this,  as  well  as  for  other  reasons  subsequently  to  be 
referred  to,  the  connections  existing  between  the  several 

*  perceptive  centres '  for  such  impressions  (especially  those 
of  Touch  and  Sight),  and  the  KinjBsthetic  Centre  must 
be  peculiarly  intimate  and  complex. 

Each  'special'  Perceptive  Centre  and  also  the  'visceral' 
*  Loc.  cit.  p.  2C8. 


Chap.  XXVII.]    CEREBRAL  MENTAL  SUBSTRATA.  593 

Centre  may,  at  times,  and  according  to  the  nature  of  the 
stimukis,  form  the  starting  point  both  in  'sensori-motor' 
and  in  ^ideo-motor' Acts,  whence  outgoing  stimuli  issue 
to  rouse  the  Motor  Centres.  But  whether  these  im- 
pulses pass  off  from  such  'special'  or  'visceral'  Centress 
directly,  or  whether  (without  our  consciousness)  they  pass 
from  them  to,  and  then  off  from,  some  parts  of  the  Kin- 
aesthetic  Centres  must  be  considered  to  remain,  for  the 
present,  very  uncertain. 

On  other  occasions,  either  of  the  '  special '  Perceptive 
Centres  may  receive  impressions  which  form  the  initial 
starting  points  of  currents  ending  in  Voluntary  Acts  ; 
though  the  immediate  execution  of  the  Movement  thus 
prompted  may,  in  the  case  of  the  majority  of  limb-move- 
ments, be  dependent  upon  the  secondarily  excited  guidance 
of  co-active  Visual  and  Kinsesthetic  Centres — just  as  in 
the  case  of  the  complex  movements  concerned  in  Articu- 
late Speech,  the  immediate  execution  of  such  movements 
is  dependent  upon  the  regulative  activity  of  the  combined 
Auditory  and  Kinsesthetic  Centres.* 

Owing  to  the  great  preponderance  of  movements  of  the 
right  arm  and  hand,  as  compared  with  those  on  the  left  side, 
the  Kinsesthetic  Centre  of  the  left  Cerebral  Hemisphere 
would  be  much  better  developed,  in  the  great  majority  of 
persons,  than  that  of  the  right  Hemisphere.  The  impres- 
sions of  the  Kinaesthetic  Sense  are,  in  this  respect,  pre- 
cisely like  those  of  Touch — and  these  two  kinds  of  sensory 
endowments,  as  we  have  seen,  merge  into  one  another 
so  imperceptibly  as  to  make  it,  in  part,  impossible  to 
separate  their  Cerebral  Centres  from  one  another. 

This  preponderating  activity  of  the  left  Cerebral  Hemi- 
sphere in  regard  to  Tactile  and  Kingesthetic  Impressions 
(about  which  there  is  no  room  for  doubt)  may  have  some- 
*  See  p.  555,  and  Chap.  xxix. 


594       CEREBRAL  MENTAL  SUBSTRATA. 

thing  to  do  with  another  fact,  viz.,  that  the  left  Hemi- 
sphere is  the  most  potent,  and  seems  to  take  the  lead  iii 
giving  rise  to  the  Voluntary  Impulsions  which  determine 
the  muscular  acts  involved  in  Articulate  Speech.'^ 

In  regard  to  our  *  ideas  '  of  Words — the  symbols  with 
which  our  Thoughts  are  inextricably  interwoven — these 
are,  for  the  most  part,  complex,  the  components  (as  in 
the  case  of  simple  Perceptions)  being  dependent  upon  the 
activity  of  different  Centres — which  need  not  always  act 
together — and  in  their  order  of  importance  are  probably 
to  be  enumerated  as  the  Auditory,  the  Visual,  and  the 
Kina)sthetic. 

Of  these  modes  of  *  ideal '  recall  of  Words,  the  two 
former  are  distinct  and  easily  recoverable,  while  the  latter 
is  characteristically  vague  and  difficult  of  conscious 
realization.  Let  any  one  contrast  his  idea  of  the  sound 
of  the  word  '  London,'  or  his  idea  of  the  appearance  of  the 
word  when  printed  or  written,  with  his  idea  of  the  mus- 
cular and  other  feelings  associated  with  the  articulation  of 
the  same  word,  and  the  inferiority  in  definiteness  and 
recoverability  of  the  latter  will  at  once  become  obvious. 
There  is  nothing  surprising  in  this,  however,  since  we 
know  that  the  tendency  of  KinjDsthetic  Impressions 
generally  is  that  they  should,  like  Visceral  Impressions, 
soon  come  to  affect  the  motor  machinery  of  our  bodies 
without  arousing  our  Consciousness.  In  such  animals  as 
are  born  with  their  motor  acquirements  already  well-nigh 
complete  (pp.  188,  229),  Kinoesthetic  Impressions  probably 
enter  as  little  into  their  conscious  Mental  Life  as  mul- 
titudes of  Visceral  Impressions  enter  into  our  own. 

Speech  has  already  become,   for    the   human   race,    a 

*  See  p.  403,  and  also  Dr.  Lombard  in  "  Proceed,  of  the  Koyal 
Society/'  1878,  pp.  463,  464. 


Chap.  XXVIL]    CEREBRAL  iMENTAL  SUBSTRATA.  595 

much  more  *  iiistiuctive '  act  than  Writiiij]^,  so  that  it  is 
moreiy  a  result  of  the  tendency  ahove  alluded  to  that  the 
Kiiui}sthetic  Impressions,  pertaining  to  the  more  deeply 
ingrained  motor  acts,  have  become  proportionately  more 
vague  and  irrecoverable.  Be  this  explanation  correct  or 
not,  the  fact  itself  is  obvious.  Let  any  one  shut  his  eyes, 
place  his  fingers  in  the  position  for  writing,  and  make  in 
the  air  such  movements  as  would  be  needed  for  writing 
the  word  '  London ; '  immediately  afterwards  let  him 
articulate  the  same  word  and  compare,  in  regard  to 
relative  distinctness,  the  two  sets  of  Kinaesthetic  Impres- 
sions. The  difference  appears  to  the  writer  to  be  most 
marked. 

The  fact  that  Thought  in  a  child,  or  in  an  '  absent-minded  * 
person,  is  apt  to  be  accompanied  with  muttered  Articulations  may 
be  easily  understood  when  we  consider  to  what  an  extent  Speech 
soon  becomes  a  mere  reflex  or  '  ideo-motor '  act,  and  that  the 
phenomenon  in  question  occurs  especially  in  those  persons,  or  under 
those  conditions,  in  which  Volitional  Control  is  in  abeyance  and 
reflex  actions  are  most  prone  to  manifest  themselves.  Again,  that 
Articnla,tion  should  (where  it  is  not  intended)  so  frequently  accom- 
pany the  attempt  to  read  made  by  an  illiterate  person  or  by  a 
child,  is  simply  due  to  the  fact  that  during  the  process  of  learning 
to  read  (from  which  they  have  not  yet  emerged),  their  attempts 
are  always  accompanied  by  vocal  articulations — as  in  the  process 
of  reading  aloud  to  a  teacher.  To  stop  at  the  mere  realization  of 
the  Visual  Impression,  and  thus  undo  their  previous  habit,  is  aii 
accomplishment  to  which  these  persons  and  many  children  have 
not  yet  attained. 

To  speak,  therefore,  of  the  '  ideas '  of  Words  as  *  motor 
processes,'  or  to  say  that,  **  a  suppressed  articulation  is, 
in  fact,  the  material  of  our  recollection,  the  intellectual 
manifestation,  the  idea  of  Speech,"  is,  in  the  writer's 
opinion,  both  misleading  and  erroneous — though  the  latter 
is  a  view  which  has  been  put  forth  and  advocated  by 
no  less  an  authority  on  psychological  subjects  than  Pro- 


596       CEREBRAL  MENTAL  SUBSTRATA. 

fessor  Bain.*  That  mental  representative  of  a  Word 
which  is  least  distinct  and  most  difficult  to  revive  (what- 
ever may  be  the  view  entertained  as  to  its  precise  nature 
and  origin),  is  here  declared  to  be  of  most  importance  in 
regard  to  Thought  and  Speech  processes — as  of  so  much 
importance  that  it  is  spoken  of  by  Prof.  Bain  as  con- 
stituting the  "  material  of  our  recollection  "  in  the  use 
and  production  of  Words,  whilst  no  mention  is  in  this 
place  made  of  other  (auditory  and  visual)  modes  of  revival. 
Again,  relying  much  upon  the  above  and  allied  doc- 
trines, Dr.  Hughlings  Jacksonf  has  repeatedly  and  in  the 
most  forcible  manner,  urged  his  own  view  that  '^men- 
tal operations  in  the  last  analysis  must  he  merely  the 
suhjeclive  side  of  sensory  and  motor  substrata.''  For 
those  who  hold,  as  Hughlings  Jackson  does,  the  view 
of  Bain,  Wundt,  and  others,  to  the  effect  that  our 
Consciousness  of  *  muscular  activity'  is  in  great  part 
initial,  centric  and  realizable  in  the  Motor  Centres — this 
mode  of  expression  is  legitimate  enough  :  it  is,  in  fact, 
its  logical  outcome.  But  for  those  who  wholly  disbelieve 
this  general  doctrine,  as  Dr.  Ferrier  does,  and  who  regard 
all  sensations  or  impressions  connected  with  Movement  as 
derivable  from  peripheral '  ingoing '  impressions  emanating 
from  the  moving  parts  themselves,  and  not  going  back 
to  the  Cerebrum  along  motor  nerves,  such  an  opinion  and 
such  modes  of  expression  would  be  altogether  inadmissible. 

*  "  The  Senses  and  the  Intellect,"  3rd  Ed.,  p.  336.  It  is  true 
that  in  other  parts  of  the  same  work  {e.g.,  on  p.  436)  Prof.  Bain, 
in  a  contradictory  manner,  refers  to  sensory  elements  of  the  auditory 
type  as  the  most  important  components  of  our  memory  of  spoken 
lan<,ni!ige;  but  this  in  no  way  diminishes  his  resiwnsibility  for  tho 
emphasised  statement  above  quoted.  (See  "  Fortnightly  Review," 
Ap.  1869,  p.  493.) 

f  "  Clin,  and  Physiolog.  Hesearch  on  the  Nervous  System,'* 
(Beprint),  1876,  pp.  xx-xxxvii. 


Chap.  XXVII.]    CEREBRAL  MENTAL  SUBSTRATA.  597 

Yet,  strangely  enough,  this  latter  able  writer  and  experi- 
menter, whose  views  are  likely  to  exercise  considerable 
influence,  seems  to  have  been  betrayed  into  such  an  in- 
consistency.* 

If  the  various  impressions  which  go  to  make  up  the  Kinassthetio 
Sense  are  all  of  them  (as  we  suppose)  real  'ingoing'  impressions 
that  traverse  different  kinds  of  sensory  nerves,  the  mere  difference 
of  the  mode  or  occasion  on  which  they  are  excited,  should  not  lead 
to  their  being  spoken  of  as  though  they  were  radically  different  in 
nature  from  other  sensory  impressions.  So  that  in  accordance  with 
this  view,  the  dictum  '  nihil  est  in  intdlectu  quod  non  fuerit  prius 
in  sensu '  loses  none  of  its  old  force — it  is  a  formula  broad  enough 
to  include  the  Kinsesthetic  and  Visceral  as  well  as  the  Special 
Senses— and  if  incorrect,  would  be  so  as  much  in  the  one  as  in  the 
other  direction. 

Terrier  truly  saysf: — "By  the  movements  of  the  head  and  eyes 
we  greatly  extend  the  scojie  and  complicate  the  facts  of  visual 
sensation,  and  by  the  movements  of  the  limbs  the  range  of  tactile 
experience  is  increased  a  thousandfold."  But  he  conveys  (from  his 
own  previous  point  of  view)  a  contradictory  and  erroneous  implica- 
tion when  he  adds  : — "  There  are  few  objects  of  cognition  known 
to  us  only  by  sensory  characters  or  impressions.  The  vast  majority 
involve  the  activity  both  of  our  sensory  and  motor  faculties,  and 
our  ideas  are  a  mixed  revival  both  of  ideal  movements  and  ideal 
sensations  in  their  respective  coherent  associations.  This  is  exem- 
plified in  the  acquisition  and  constitution  of  ideas  of  form,  shape, 
weight,  resistance  and  the  like." 

A  view  of  this  kind  (viz.,  that  'ideal  movements'  have  a  basis 
other  than,  and  wholly  opposed  to,  that  usually  known  as  '  sensory ') 
is  one  now  commonly  held,  and  is  altogether  similar  to  that 
taught  in  this  country  by  Prof.  Bain.  He,  for  instance,  when 
speaking  of  Sight,  has  said  J  it  "is  now  generally  considered  as  a 
mixed  sense,  and  that  the  visual  sensations  are  partly  muscular 
feelings   and  partly  optical   feelings."      He  adds: — "In  all  that 

*  This  may  be  seen  by  comparing  Ferrier's  examination  of  the 
'  muscuhir  sense '  question  ("  Functions  of  the  Brain,"  pp.  215-227), 
with  his  views  and  modes  of  expression  in  Chap,  xi.,  some  state- 
ments in  which  are  now  about  to  be  referred  to. 

t  Loc.  cit.  p.  267.     X  "  Fortnightly  Review,"  April,  1869,  p.  498. 


598       CEREBRAL  MENTAL  SUBSTRATA. 

regards  visible  movements  and  visible  form,  the  muscular  con* 
sciousness,  it  is  now  contended,  is  the  indispensable  element; 
the  optical  sensations  merely  guiding  the  movements.  Naked 
outlines,  as  the  diagrams  of  Euclid  and  the  alphabetical  charac- 
ters are,  to  say  the  least,  three  parts  muscular  and  one  part 
optical,  their  retention  is  supposed  to  depend  upon  the  adhesive 
joroperty  of  the  ocular  muscles  and  their  nerve  centres,  and 
not  upon  purely  optical  circles.  The  memory  of  a  visible  form, 
as  a  rainbow,  contains  the  consciousness  of  a  muscular  sweep; 
the  windings  of  a  river  which,  in  the  actual  view,  have  to 
be  followed  by  movements  of  the  eye,  are  remembered  as  ideal 
movements." 

Without  questioning  the  undoubted  fact,  that  the  movements  of 
a  sensory  organ  must  greatly  increase  the  variety  of  impressions 
derivable  therefrom,  or  that  they  may  contribute  notably  to  generate 
in  the  mind  of  the  individual  the  fundamental  notion  of  modes  of 
existence  known  as  '  space,' '  time,'  and  '  resistance,'  it  is  nevertheless 
open  for  each  one  of  us  to  form  his  own  opinion  as  to  the  extent  to 
which  '  muscular  consciousness '  reveals  itself  to  us  as  interwoven 
with  our  ordinary  sight  impressions,  and  many  may  perhaps  be 
inclined  to  think  they  can  detect  far  less  of  it  than  Prof.  Bain. 
It  is  also  open  to  each  one  of  us  to  take  a  different  view  as  to 
the  meaning  and  nature  of  what  Prof.  Bain  here  speaks  of  as  '  mus- 
cular consciousness.'  He,  we  know,  regards  it  as  a  '  concomitant 
of  the  outgoing  current,'  and  upon  this  basis  considers  it  to  be 
radically  opposed  to  all  other  modes  of  sensibility — though  this  is 
a  view  which  others  have  just  as  decidedly  rejected. 

For  those,  however,  who  entertain  this  disbelief  in  the  existence 
of  a  '  muscular  sense'  or  '  muscular  consciousness '  as  a  concomi- 
tant of  the  'outgoing'  current,  and  who  consider  that  the  know- 
ledge attributed  to  such  an  endowment  has,  in  reality,  been  ac- 
quired by  means  of  'ingoing'  impressions  emanating  from  the 
moving  parts  themselves,  the  revival  in  idea  of  such  knowledge 
must  be  as  purely  dependent  upon  the  activity  of  Sensory  Centres 
as  are  the  processes  concerned  with  the  revival  in  idea  of  particular 
Odours. 

Tho  seats  of  revival  in  idea  of  Movements  of  parts  of  the  body 
which  are  not  seen  {e.g.,  those  of  the  larynx  or  of  the  eyes),  are 
the  Kina3stheiic  Centres  alone;  whilst  in  the  case  of  Movements 
of  parts  of  the  body  that  are  habitually  seen — Movements  which 
havei:jerhaj)S  been  learned  under  additional  guidance  from  Vision — • 


Chap.  XXVII.]    CEREBRAL  MENTAL  SUBSTRATA.  51)^ 

a  double  or  mixed  ideal  recall  occurs,  partly  having  its  organic  basia 
in  tlie  Kin;csthe+ic  and  partly  in  the  Visual  Centres. 

It  seems,  therctbre,  not  a  little  inconsistent  to  find  Ferrier  (who 
rejects  the  doctrine  of  Bain  and  Wundt)  writing  as  follows : — *'  In 
tlie  same  manner  as  the  sensory  centres  form  the  organic  basis  of 
tlie  memory  of  sensory  impressions,  and  the  seat  of  their  repre- 
sentation or  revival  in  idea,  so  the  motor  centres  of  the  hemi- 
spheres, besides  being  the  centres  of  differentiated  movements,  are 
q\so  the  organic  basis  of  the  memory  of  the  corresponding  move- 
ments, and  the  seat  of  their  re-execution  or  ideal  reproduction* 
We  have  thus  a  sensory  memory  and  a  motor  memory,  sensory 
ideas  and  motor  ideas ;  sensory  ideas  being  revived  sensations, 
motor  idea£  heing  revived  or  ideal  movements.  Ideal  movements 
form  no  less  an  im-portant  element  in  our  m^ental  processes  than 
ideally  revived  sensations.*^ 

There  is  here  an  obvious  confusion  between  two  totally  distinct 
centres  and  processes.  Ferrier,  in  fact,  by  rejecting  the  doctrine  of 
Bain  and  Wundt  in  reference  to  the  'muscular  sense,'  or  'muscle 
consciousness,'  rejected  the  natural  basis  upon  which  Hughlings 
Jackson  originally-  founded  his  h3'pothesis,  as  to  the  existence  of 
*  motor  centres  '  in  the  Cerebral  Convolutions.  Yet  on  coming  to  his 
Chap,  xi.,  "The  Hemispheres  considered  Psychologically,"  Ferrier 
writes  as  though  he  had  forgotten  this  previous  rejection,  and  the 
whole  discussion  to  which  he  had  devoted  pp.  215-227  of  his  work. 
He  has,  therefore,  on  the  one  hand,  striven  to  localize  *  motor 
centres*  in  the  Cerebral  Convolutions,  and,  on  tlie  other  hand,  he 
has  deliberately  rejected  that  interpretation  of  the  philosophical 
an(i  physiological  evidence  upon  which  the  existence  of  any  such 
centres  must  rest. 

Motor  centres,  wherever  they  may  he  situated,  are  parts 
whose  activity  appears  to  be  wholly  free  from  subjective 
concomitants.  No  '  ideal '  reproductions  seem  ever  to  take 
place  in  such  centres ;  they  are  roused  into  activity  by 
outgoing  currents,  and,  so  far  as  we  have  any  evidence, 
the  induction  in  them  of  molecular  movements  which, 
immediately  afrerwards,  issue  through  cranial  and  spinal 
Motor  Nerves  to  Muscles  are  simply  physical  phenomena. 

*  Italics  not  in  the  original  (loc^  cit.  p.  266). 


600       CEREBRAL  MENTAL  SUBSTRATA. 

These  processes  are  apparently  as  free  from  subjective  acconi' 
paniments  as  are  the  actual  molecular  processes  thereby  in- 
cited in  the  Muscle  itself.  It  is  the  altered  condition  of  the 
Muscle  thus  induced,  and  of  contiguous  parts  as  occa- 
sioned by  the  Movement,  which  together  engender  a  body 
of  ingoing  impressions,  the  terminus  for  which  is  the 
Kinsesthetic  Centre.  This,  therefore,  is  a  true  Sensory 
Centre,  and  in  it  '  ideal  movements  '  may  be  revived,  either 
alone  or  conjointly,  with  related  Visual  Impressions. 

The  Kinsesthetic  Centre  is,  indeed,  one  of  great  impor- 
tance. Its  impressions  enter  inextricably  into  a  large 
majority  of  our  mental  processes — as  widely  and  inextric- 
ably, in  fact,  as  the  assumed  '  muscular  consciousness  * 
of  Bain  is  supposed  by  him  and  others  to  be  intertwined 
with  what  they  would  distinguish  as  '  passive '  sensibilities. 
But  it  can  only  produce  an  extreme  amount  of  confusion, 
if  the  activity  of  this  Sensory  Centre  is  attributed  to  and 
confounded  with  that  of  Motor  Centres,  the  processes  of 
which  seem  to  lie  even  more  truly  outside  the  sphere 
of  Mind  than  the  molecular  processes  comprised  in  the 
actual  contraction  of  a  Muscle :  these  latter  processes  are 
at  least  immediately  followed  by  'ingoing'  impressions, 
whilst  so  far  as  we  know — that  is  so  far  as  any  evidence 
exists — the  former  are  not. 

The  Cerebral  substrata  of  Mind,  therefore,  in  no  way 
include,  as  the  writer  believes,  the  processes  taking  place 
in  the  Motor  Centres  of  the  Cerebrum,  wheresoever  they 
may  be  situated.  Mental  operations,  in  other  words,  can  no 
longer  be  legitimately  postulated  as  being,  in  part,  imme- 
diately due  to  the  activity  of  Motor  Centres.  Nor  can 
'ideal'  Words  be  rightly  described  as  *  motor  processes.* 
This  is  a  point  so  fundamental  that  in  regard  to  it  there 
should  be  no  misunderstandings  or  ambiguities,  other  than 
those  which  may  be  inherent  in  the  subject  itself. 


CHAPTER  XXVIIL 

BPEAKINO,     READING,    AND    WRITING  :    AS     MENTAL    AND    AS 
PHYSIOLOGICAL   PROCESSES. 

The  views  arrived  at  in  the  last  chapter  will  be  found 
to  harmonize  well  with  what  is  known  as  to  the  mode  in 
which  the  faculty  of  Articulate  Speech,  together  with 
the  superadded  accomplishments  of  Reading  and  Writing, 
are  acquired.  A  preliminary  consideration  of  these  sub- 
jects will,  moreover,  facilitate  our  comprehension  of  the 
various  defects  in  the  power  of  Intellectual  Expression 
(whether  by  Speech  or  Writing)  liable  to  be  produced  by 
different  kinds  of  Brain-disease  :  and  the  study  of  the  latter 
subject  is  most  important  for  the  psychologist.  Its  inves- 
tigation has  already  revealed  some  very  interesting  facts  as 
to  the  order  and  precise  relations  of  various  mental  pro- 
cesses, as  well  as  concerning  their  relationship  to  the  func- 
tional activity  of  particular  tracts  of  Brain-tissue.  We 
are,  indeed,  in  this  manner  afforded  the  nearest  approach 
that  is  possible  to  an  experimental  investigation  of  such 
subjects.  A  close  scrutiny  of  the  necessary  details  will, 
whilst  furthering  our  knowledge,  serve  also  (as  a  result 
of  this  knowledge)  to  increase  our  chance  of  being  able  to 
bring  amelioration  to  the  sufferers  themselves. 

That  Thought  in  all  its  higher  modes  cannot  be  carried 

on  without  the   aid  of  Language  is  a  proposition  which 

will  be  almost  universally  admitted  if  we  use  the  latter 

term    in  its  broadest    sense.     For,    as    Thomson    says,* 

*  "  Laws  of  Thought,"  18G0,  p.  27. 


602      SPEAKING,  READING,  WRITING  :    AS  MENTAL 

"  Language,  in  its  most  general  acceptation,  might  be 
described  as  a  mode  of  expressing  our  thoughts  by  means 
of  motions  of  the  body  ;  it  would  thus  include  spoken 
words,  cries,  involuntary  gestures  that  indicate  the  feel- 
ings, even  painting  and  sculpture,  together  with  those 
contrivances  which  replace  speech  in  situations  where  it 
cannot  be  employed."  Articulate  Speech,  in  one  or  other 
of  its  modes,  is,  however,  the  process  which  (for  ordinary 
human  beings)  is  found  to  be  inseparably  related  with 
their  Thinking  processes.  Speech  is,  indeed,  nothing 
else  than  *'a  system  of  articulate  words  adopted  by  con- 
vention to  represent  outwardly  the  internal  process  of 
Thinking." 

Taking  the  Human  Race  at  the  present  stage  of  its 
history,  when  most  elaborate  Languages  have  long  ago 
been  acquired  by  different  sections  of  it,  w^e  may  now 
briefly  set  forth  the  principal  steps  by  which  individual 
children  learn  to  understand  one  of  these  languages  ;  how 
afterwards  they  learn  to  Speak,  to  Read,  and  to  Write ; 
and  to  what  extent  the  symbols  involved  in  these  various 
processes  recur  to  the  Mind  as  the  framework  of  Thought. 

A  brief  sketch  of  the  nature  of  the  processes  involved 
in  these  acquisitions  was  attempted  by  the  writer  in  1869, 
in  an  article*  entitled  the  "Physiology  of  Thinking," 
and  from  this  a  few  quotations  may  now  be  made. 

*'  The  young  infant  first  begins  to  distinguish  natural 
objects  from  one  another  by  differences  in  shape,  colour, 
touch,  odour,  etc.,  which  these  may  present  to  its  different 
senses  ;  it  is  then  taught  (slowly  and  with  difficulty)  to 
associate  some  object  possessing  certain  combined  attributes 
by  which  it  is  remembered,  with  a  certain  articulate  sound 
which  has  been  often  repeated  whilst  the  object  is  pointed 
at,  till  by  dint  of  continual  repetition  this  sound  (or  word) 
*  "  Fortiiiglitly  Review,"  January,  1869. 


Chap.  XXYIII  ]    AND  PHYSIOLOGICAL  PROCESSES.  603 

becomes  so  identitied  with  the  various  attributes  of  the 
object  that,  when  heard,  it  invariably  recalls  to  memory 
the  object  of  which  it  may  now  be  said  to  form  a  kind  of 
additional  attribute,  just  as  the  sight  or  touch  of  the  object 
will  in  turn  call  up  the  memory  of  the  sound  which  has 
been  employed  as  its  designation.  At  first  these  articu- 
late sounds  (or  spoken  words)  are  only  connected  with 
external  objects,  though  soon  certain  adjectives,  signifying 
approval  or  disapproval,  are  added  as  qualifying  sounds. 
By  degrees  the  number  of  nouns  and  of  adjectives  in  use 
increases,   and    also   other   parts  of    speech   are   added. 

the  process  of  learning  is  the  same  in  all 

cases,  whether  the  spoken  sound  is  to  be  associated  with 
an  external  object,  with  an  emotional  condition,  or  with 
a  conception  of  the  mind  :  first,  it  is  necessary  that  we 
should  be  able  to  recollect  and  identify,  when  again  pre- 
sented to  consciousness,  either  the  set  of  attributes 
belonging  to  the  object,  the  peculiarities  of  the  emotional 
state,  or  of  the  intellectual  conception  ;  and,  secondly, 
that  we  should  be  able  to  recollect  the  particular  vocal 
sounds  which  have  been  associated  with  these  several 
modifications   of  consciousness  v/hen  previously  existing. 

This  is  the  first  stage  passed  through  in 

the  acquirement  of  a  language — it  is  the  mere  learning 
to  associate  particular  sounds  with  particular  mental  im- 
pressions, which  association  at  last  becomes  so  strong  as 
to  be  almost  inseparable,  the  thing  unfailingly  recalling 
to  memory  the  sound,  and  the  articulate  sound  as  surely 
conjuring  up  a  more  or  less  vivid  idea  of  the  thing.  In 
the  process  of  Naming,  therefore,  there  is  involved  not 
only  a  simple  act  of  memory,  but  also,  as  Herbert  Spencer 
has  pointed  out,  the  germ   of  a   reasoning  process  in  the 

form  of  a  simple  act  of  inference it  would 

seem  pretty  obvious  that   so   far  as   the  infant  thinks  by 


C04      SPEAKING,  READING,  WRITING:    AS  MENTAL 

means  of  language,  it  does  so  by  means  of  the  remembered 
soiuids  of  words — these  are  its  linguistic  symbols  of 
thought,  which  must,  however,  be  mixed  up  inextricably 
in  its  mind  with  other  sense-impressions,  and  more 
especially  with  those  of  sight.  For  it  may  fairly  be  said 
that  the  great  majority  of  children  can  remember  the 
names  given  to  many  external  objects  when  they  are  four 
or  five  months  old ;  their  memory  in  this  respect  con- 
tinually increasing  through  succeeding  months,  even  whilst 
they  still  make  no  very  distinct  effort  at  articulating  words 
for  themselves." 

The  next  step  is  the  development  or  acquirement  by 
the  individual  child  of  the  power  of  articulating  for  him- 
self the  sounds  which  have  hitherto  been  increasingly 
employed  as  mental  symbols.  The  potentiality  of  attain- 
ing to  such  a  power  the  child  receives,  in  the  main,  as  an 
inheritance  from  so  many  antecedent  generations  of  men, 
that  its  actual  manifestation — the  acquisition,  that  is,  of 
the  power  of  Speaking — can  only  be  regarded  as  a  motor 
achievement  of  an  order  similar  to  some  of  those  which 
may  be  included  among  the  Instinctive  Acts  of  lower 
animals :  the  similarity  being  not  so  much  with  the 
Instinctive  Acts  that  animals  are  born  with  the  capacity 
of  performing,  but  rather  with  those  which  manifest 
themselves  a  little  later  in  life,  and  which  (from  their 
more  gradual  acquirement)  might  be  thought  not  to  be 
Instinctive  Acts  at  all  (p.  561). 

A  process  of  '  learning '  to  Speak  intervenes  in  part 
in  the  former  case,  but  it  is  whilst  the  inherited  struc- 
tures are  undergoing  development  in  the  child's  Nervous 
System. 

"  A  certain  order  of  development  is  always  observed  in 
the  various  parts  of  the  human  body,  and  this  holds  good 
also  with    regard    to   the  several   parts    of    the    nervoua 


CuAt.  XXVIII.]    AND  PHYSIOLOGICAL  PROCESSES.  605 

sj'stem Even  though  the  child  acquires  tho 

2^ower  of  uttering  articulate  sounds  slowly,  still  when  we 
think  of  the  delicacy  of  the  muscular  combinations 
necessary,  and  of  the  almost  instinctive  way  in  which 
they  are  brought  about,  we  shall  rather  be  impressed  with 
the  notion  that  this  could  not  have  been  accomplished  at 
all  had  not  the  infant  been  born  with  a  nervous  system 
tending  to  develop  itself  in  certain  special  directions,  and 
thus  making  the  performance  of  the  highly  complex 
muscular  acts  necessary  for  articulate  speech  a  possibility. 
Slowly  elaborated  developments  of  the  parts  of  the 
Medulla  and  of  the  Brain  concerned  in  the  acts  of  speech, 
we  may  presume  had  taken  place  in  remote  individuals 
of  the  parent  race,  as  they  acquired  additional  powers 
in  this  I  spect  ;  and  the  power  of  developing  similar 
structural  connections  between  nerve  cells  and  nerve 
fibres,  thus  established,  having  been  handed  down  and 
gradually  rendered  more  perfect  by  hereditary  transmis- 
sion through  countless  succeeding  generations,  the  infant  of 
to-day  is  born,  perchance,  with  the  potentiality  of  develop- 
ing a  nervous  system  as  complex  and  as  perfect  in  this 
respect  as  any  which  may  have  preceded  it  in  its  own 
ancestral  line."  A  slowly  growing  mechanism  of  this  kind 
becomes  perfected  under  the  influence  of  suitable  stimuli 
of  a  volitional  order,  which  here,  as  in  the  case  of  the 
acquirement  of  new  motor  powers  by  an  adult,  have  an 
unquestionable  though  an  unexplained  influence  in  bring- 
ing about  the  development  of  nerve-tissues  in  the  Centres 
to  which  they  are  directed  (see  p.  563).  "  This  impetus, 
we  may  presume,  is  given  by  the  passage  of  nerve-currents 
downwards  from  those  superficial  portions  of  the  cerebral 
hemispheres  concerned  in  the  acts  of  intellectual  percep- 
tion and  of  memory,  to  those  parts  which  are  the  motor 
centres  concerned  in  articulate  speech." 


606      SPEAKING,   READING,  WRITING  :    AS  MENTAL 

**  At  first  the  child's  articulatory  capacity  is  confined 
to  mimicking — that  is  to  say,  it  repeats  such  words  only 
as  have  just  been  spoken  to  it ;  hut  after  a  time,  when 
the  act  of  emitting  this  sound  has  become  perfectly  easy 
by  constant  repetition,  the  child  gives  utterance  to  it  of 
its  own  accord,  on  the  mere  sight  of  the  object  with 
which  the  sound  was  originally  associated  in  its  mind. 
This  then  is  the  second  stage  in  the  acquirement  of  lan- 
guage ;  and  the  child  only  slowly  attains  to  a  more  perfect 
performance  of  the  mental  and  motor  processes  involved.'* 
After  a  time,  however.  Thought  and  Language  become  in- 
separably associated,  so  that  words  are  voluntarily  recalled 
by  the  renewal  of  previous  nerve  actions  in  the  Auditory 
Perceptive  Centres,  and  such  nerve  processes  are  followed 
by  the  complex  combination  of  muscular  actions  concerned 
in  the  articulation  of  the  several  words  as  they  arise  in 
Thought. 

Since  the  foregoing  views  were  expressed  and  pub- 
lished, the  writer  has  met  with  an  altogether  unexpected 
confirmation  of  their  truth.  In  the  year  1877  he  was 
consulted  concerning  the  health  of  a  boy,  the  son  of  a 
leading  barrister,  who  was  then  twelve  years  old,  and 
had  been  subject  to  *  fits  '  at  intervals.  The  first  fits 
occurred  in  infancy,  when  the  patient  was  about  nine 
months  old.  Towards  the  end  of  the  second  year  these 
fits  seemed  to  have  ceased,  and  the  child  appeared  suffi- 
ciently intelligent — to  be  well,  in  fact,  in  all  respects  except 
that  he  did  not  talk.  When  nearly  five  years  old  the  little 
fellow  still  had  not  spoken  a  single  word,  and  about  this 
time  two  eminent  physicians  were  consulted  in  regard  to 
his  '  dumbness.'  But  before  the  expiration  of  another 
twelve  months,  as  his  mother  reports,  on  the  occasion  of 
an  accident  happening  to  one  of  his  favourite  toys,  he  sud- 
denly exclaimed,  "  What  a  pity  !  "  though  he  had   never 


Chap.  XXVIIL]    AND  PHYSIOLOGICAL  PROCESSES.  607 

previously  spoken  a  single  word.  The  same  words  could 
not  be  repeated,  nor  were  others  spoken,  notwithstanding 
all  entreaties,  for  a  period  of  two  weeks.*  Thereafter  the 
boy  progressed  rapidly,  and  speedily  became  most  talk- 
ative. When  seen  by  the  writer  he  spoke  in  an  ordinary 
manner,  without  the  least  sign  of  impediment  or  defect.+ 
No  explanation  of  such  facts  seems  possible,  except  on 
the  supposition  that  Speech  has  now  become  a  truly 
automatic  act  for  human  beings,  and  that  if  children  do  not 
speak  at  birth  this  is  in  the  main  due  to  the  fact  that 
their  nervous  systems  are  still  too  immature.  But  when, 
in  the  natural  course  of  development,  the  parts  concerned 
have  become  properly  elaborated,  the  highly  complex  move- 

*  An  emotional  is  much  stronger  than  a  volitional  stimulus — 
a  thing  of  higher  tension — so  that  it  may  occasionally  force  its  way 
along  channels  and  against  resistance  which  the  volitional  stimulus 
alone  has  been  unable  to  overcome.  Illustrations  of  this  are  fre- 
quently to  be  met  with  among  persons  who,  from  the  effects  of 
disease,  have  temporarily  lost  the  power  of  speaking.  Such  indi- 
viduals occasionally  utter  some  wo'-d  or  short  phrase  under  the  in- 
fluence of  Emotion  which  they  are  afterwards  quite  unable  to  repeat. 

f  Although  there  seemed  no  room  for  doubt  as  to  the  credibility 
of  the  above  narrative,  still,  on  account  of  the  extraordinary  nature 
of  the  facts,  it  may  be  well  to  remark  that  it  was  completely  con- 
firmed by  the  governess  who  had  previously  had  the  care  of  the 
child,  and  who  was  present  on  the  occasion  of  this  first  and  un- 
taught act  of  Articulate  Speech.  A  proof  of  this  sheet  has  also 
been  submitted  to  the  father,  who,  in  reply  to  my  enquiry  as  to 
whether  anything  required  to  be  altered  in  the  account  above  given, 

writes  (Jan.  9th,  1880) : — "  The  statement  as  to  my  boy  A is 

perfectly  correct."  On  mentioning  this  case  to  a  distinguished 
physician,  he  informed  me  of  a  closely  related  fact.  His  eldest 
daughter  up  to  the  age  of  two  years  had  not  walked  a  step,  or  even 
tried  to  walk,  when  one  day  he  put  her  down  in  the  standing  position, 
and  to  his  great  surprise  as  well  as  to  that  of  the  nurse,  she  walked 
from  one  side  of  the  room  to  the  other.  Thin  also  was  an  untaught 
act,  as  there  had  been  no  previous  trials  and  failures  (see  p.  562). 


608      SPEAKING,  READING,  WRITING  :    AS  MENTAL 

ments  concerned  in  Speech  may,  under  certain  circum- 
stances, be  at  once  called  into  play,  independently  of  pre- 
vious trials  and  failures — just  as  the  nervous  mechanism 
concerned  with  the  act  of  sucking  may  be  called  into  play 
in  the  human  infant  at  the  time  of  birth,  on  the  presen- 
tation of  its  proper  stimulus.  No  such  untaught  acts  of 
Speech  would  however  be  possible,  unless  development  had 
been  taking  place  in  the  normal  manner,  and  unless  the 
Auditory  Sense  and  Intelligence  were  unaffected.  The 
manifestation  of  attempts  at  Speech  are  supposed  in  this 
case  to  have  been  merely  retarded  by  some  slight  and 
quasi-accidental  conditions,  such  as  are  occasionally  opera- 
tive in  childhood — especially  in  those  who  sutler  from 
epileptic  or  other  convulsions. 

Without  an  instance  of  this  sort  coming  almost  under 
one's  own  cognizance,  neither  the  writer  nor  any  one  else 
might  have  been  inclined  to  bestow  much  credence  upon 
two  very  similar  cases,  the  records  of  which  have  come 
down  to  us  from  writers  of  antiquity.* 

The  son  of  Croesus  who,  according  to  Herodotus, f  had 
never  been  known  to  speak,  and  whose  cure  had  been  in 
vain  attempted,  was,  at  the  siege  of  Sardis,  so  overcome 
with  astonishment  and  terror  at  seeing  the  king — his 
father — in  danger  of  being  killed  by  a  Persian  soldier, 
that  he  exclaimed  aloud — ArjOpcoTre  fir)  KTetve  Kpotaov — • 
**  Oh,  man,  do  not  kill  Croesus  !  "      This  was  the  tirst  time 

"*  The  real  import  of  these  latter  cases  does  not  seem  to  liave 
been  apprehended,  either  by  those  originally  recording  them  or  by 
a  modern  writer  who  has  lately  referred  to  them  (Bateman,  "  On 
Aphasia,'*  p.  138).  It  need  scarcely  be  pointed  out  that  the  sudden 
beginning  to  speak  for  the  first  time  without  previous  prolonged 
trials  and  failures,  is  a  matter  vastly  transcending  in  importance 
the  sudden  resumption  of  Speech,  when  it  has  been  for  a  while 
suspended  in  consequence  of  Brain-disease. 

t  "  Herod.,"  Hist.  I.  85. 


Chap.  XXVIII.]    AND  PHYSIOLOGICAL  PROCESSES.  609 

he  had  ever  articulated,  though  he  is  said  thereafter  to  have 
retained  the  faculty  of  Speech  as  long  as  he  lived.  Again, 
it  appears  that  Aulus  Gellius,*  after  repeating  the  above 
story  from  Herodotus,  relates  a  similar  fact  in  the  following 
terms: — "  Sed  et  quispiam  Samius  athleta,  nomen  illi  fuib 
A.ly\r}9,  quum  antea  non  loquens  fuisset,  ob  similem  dicitur 
causam  loqui  coepisse.  Nam  quum  in  sacro  certamine 
sortitio  inter  ipsos  et  adversaries  non  bona  fide  fieret,  et 
sortem  nominis  falsam  subjici  animadvertisset,  repente 
in  eum,  qui  id  faciebat,  sese  videre,  quid  faceret,  magnum 
inclamavit.  Atque  in  oris  vinculo  solutus,  per  omne  inde 
vitae  tempus,  non  turbide  neque  adhaese  locutus  est." 

The  powers  of  Reading  and  of  Writing  are  accom- 
plishments superadded  to  that  of  Articulate  Speech. 

The  child  has  already  learned  to  associate  certain  ob- 
jects, or  particular  states  of  consciousness,  with  definite 
Sounds  (or  Names)  ;  he  has  further  gained  the  power  of 
articulating  these  names  for  himself:  so  that  when  he 
begins  to  learn  to  Read,  he  gradually  builds  up  a  still 
further  '  association,'  by  which  certain  written  or  printed 
hieroglyphics,  representing  letters  in  definite  combina- 
tions, are  linked  to  the  already  known  states  of  con- 
sciousness (Perceptions,  Ideas,  &c.)  and  their  sound  repre- 
sentatives. The  previous  combinations  are  therefore  sup- 
plemented by  being  correlated  with  new  visual  symbols  ; 
and  it  seems  certain  that  in  the  act  of  Reading  the 
words  which  are  primarily  perceived  in  the  Visual  Centre 
w^ould  almost  simultaneously  recall  the  corresponding 
sounds  in  the  Auditory  Centre,  as  part  of  the  perceptive 
process  involved  in  this  act.f     From  the  Auditory  Centre 

*  "  Noctes  AtticaB,"  lib.  v.  cap.  ix. 

t  Where  this  cannot  occur  it  must  be  more  difficult  for  the 
person  to  understand  what  is  read,  and,  as  may  be  seen  from 
what  follows  (p  641),  it  may  be  impossible  for  him  to  read  aloud. 


GIO      SPEAKING,  READING,  WRITING:.  AS    MENTAL 

the  stimuli  inciting  to  tlie  articulation  of  the  corre- 
sponding words  would  then  pass  to  the  Motor  Centres 
in  precisely  the  same  manner  as  in  the  case  of  ordinary 
Speech — whatever  the  precise  course  pursued  by  these 
stimuli  may  be,  and  howsoever  they  may,  on  their 
route,  corae  into  relation  with  those  portions  of  the 
Kinesthetic  Centres  that  are  concerned  with  Speech- 
movements. 

*'  With  reference  to  the  process  of  Writing,  it  almost 
invariably  happens  that  this  accomplishment  is  acquired 
after  the  individual  has  been  taught  to  Speak  and  to  Eead 
more  or  less  perfectly.  During  this  course  of  instruction 
the  pupil  learns  to  associate  the  visual  perceptions  of  the 
separate  letters  of  words  with  certain  muscular  move- 
ments of  the  hands  and  fingers  necessary  to  enable  him 
to  produce  the  written  letters  for  himself,  and  afterwards  to 
join  them  together  so  as  to  represent  words.  This  involves 
a  long  and  tedious  process  of  education,  and  the  mus- 
cular movements  which  are  ultimately  learned  are  in  all 
probability  more  intimately  associated  with  sight-percep- 
tions than  with  sound-perceptions ;  though  of  course  the 
Word  as  a  revived  sound-perception  may  be  said  to  exist 
also  during  the  act  of  Writing.  The  muscles  of  the  upper 
extremity  being  also  to  the  fullest  extent  voluntary 
muscles,  and  therefore  very  different  from  those  concerned 
in  the  acts  of  Speech,  the  whole  process  of  learning  to 
write  is  one  which  comes  much  more  within  the  ken 
of  our  consciousness  than  does  the  otherwise  parallel 
process  of  learning  to  articulate  words." 

We  ought  therefore  to  have  much  more  power  of  re- 
calling '  in  idea  ',  either  (a)  the  '  volitional  efforts  '  that 
were  needed  to  enable  us  to  Write  words,  or  (b)  that 
*  muscular  consciousness  '  spoken  of  by  Professor  Bain 
as  representing   the  particular  states  of   tension   of  the 


CiiAP.  XXVIIL]    AND  PHYSIOLOGICAL  PROCESSES.  611 

individual  muscles  employed,  than  we  could  ever  expect 
to  have  of  the  volitional  efforts  needed,  and  of  the  states 
of  tension  of  individual  muscles  of  the  larynx  and  other 
parts  involved  in  Articulate  Speech. 

But  the  objections  to  these  two  modifications  of  the 
view  promulgated  by  Hughlings  Jackson  and  others,  that 
Words  are  revived  in  thought  as  '  motor  processes ',  have 
been  already  considered  (pp.  594,  691)  and  shown  to  be 
insuperable.  We  found  good  reasons  for  believing  that 
the  impressions  referred  to  (as  well  for  spoken  and  for 
written  words  as  for  all  other  muscular  movements)  are 
neither  anterior  to,  nor  concomitants  of  'outgoing  cur- 
rents ',  but  distinctly  sequential  to  the  passage  of  such 
currents — that  they  are,  in  fact,  due  to  '  ingoing  currents  ' 
derived  from  the  moving  parts  themselves. 

Looked  at  from  this  newer  point  of  view,  we  may  first 
consider  the  question  of  the  degree  of  detiniteness  and 
recoverability  of  the  Kinsesthetic  Impressions  derived  from 
Writing-movements. 

How  almost  impossible  is  any  such  recall  to  conscious- 
ness, and  how  vague  and  blank  a  feeling  is  associated 
with  the  attempt,  as  compared  with  the  recall  of  a  Visual 
or  of  an  Auditory  Impression,  any  one  may  easily  convince 
himself  who  will  make  the  following  simple  experiment. 
Let  him  close  his  eyes,  and  with  pen  in  hand  make  move- 
ments in  the  air  as  though  he  were  writing  the  word 
*  London.'  He  may  thus  assure  himself  that  he  has  a 
fiet  of  sensations  accompanying  these  movements.  After 
an  interval,  say  the  next  day,  let  him  again  close  his  eyes, 
and,  without  making  any  movement,  attempt  to  recall  '  in 
idea '  the  muscular  and  other  sensations  he  previously 
experienced  when  writing  the  above-mentioned  word.  Let 
him  then  contrast  his  comparative  powerlessness  in  this 
direction,  with  his  ability  to  recall  in  idea  the  visual  ap- 


612  SPEAKING,    READING,    AND    WRITING. 

pearance  of  this  word  when  written  or  its  corresponding 
sound. 

From  this  stand-point  we  may,  in  the  second  place, 
look  to  the  relative  definiteness  and  recoverability  of  the 
Kingesthetic  Impressions  consequent  upon  Speech-move- 
ments. We  may  find  then,  that  the  Impressions  which 
accompany  actual  Speech-movements  for  different  words 
can  only  vaguely  be  realized  as  distinct  from  one  another, 
and  that  they  are  certainly  far  less  distinctive  than  the 
Kinsesthetic  Impressions  derived  from  the  acts  involved 
in  Writing  different  words.  The  general  rule,  that  the 
vaguer  the  Sensation  the  lower  is  its  degree  of  recoverability 
in  Idea,  certainly  holds  good  here  also — as  any  one  may 
discover  who  will  make  the  necessary  comparative  trials. 

Thus,  slight  as  may  be  the  power  of  recalling  the 
Kinaesthetic  Impressions  derived  from  Writing,  the  ability 
to  recall  those  occasioned  by  Speech  is  even  less.  But 
that  there  should  be  such  a  difference  is  no  other  than 
might  have  been  expected,  since  a  precisely  similar  dif- 
ference obtains  in  regard  to  impressions  from  '  automatic  * 
movements  generally  as  compared  with  those  of  a  move 
*  voluntary '  order. 


CHAPTER  XXIX. 

THE    CEREBRAL   RELATIONS    OF    SPEECH    AND    THOUGHT. 

Our  powers  of  Perception  or  Apprehension,  of  Thinking 
or  Reasoning,  of  Speaking,  Naming,  Writing — even  of 
expressing  Thoughts  by  Gestures  or  the  simplest  Signs- 
are  all  dependent  upon  cerebral  processes  very  complexly 
interrelated,  as  may  have  been  gathered  from  what  has 
already  been  said.  Much  attention  has  of  late  years  been 
given  by  physicians  and  pathologists  to  the  investigation 
of  disturbances  of  the  normal  relations  existing  between 
these  several  processes,  brought  about  by  limited  lesions 
or  injuries  of  different  portions  of  the  Brain.  An  analysis 
of  some  of  the  typical  conditions  thus  revealed  will  throw 
more  light  than  could  otherwise  be  done  upon  the  manner 
in  which  Cerebro-mental  processes  are  correlated  with  one 
another.  It  will  serve  to  convey  some  faint  outline  of  the 
mode  in  w^hich  the  higher  processes  of  Sensory  Apprehen- 
sion, Thought,  and  Intellectual  Expression  (and  conse- 
quently of  '  Volition  ')  are  dependent  upon  one  another, 
and  also  of  the  mode  in  which  these  processes  are  related 
to  the  activity  of  some  imperfectly  defined  areas  in  the 
cortex  of  the  Cerebral  Hemispheres. 

What  is  now  to  be  set  forth  by  means  of  illustrations 
selected  from  some  of  the  abnormal  mental  conditions 
produced  by  Cerebral  Disease,  whilst  it  will  suffice  to  test 
and  illustrate  the  accuracy  of  the  views  expounded  in  the 
last  chapter,  may  also  be  regarded  as  the  continuation 
of  what  has  been  said  in  Chapters  xxiv.  and  xxv.  We 
27 


614  THE    CEREBRAL    RELATIONS    OF 

there  sought,  with  the  light  afforded  by  experiments  upon 
lower  animals  supplemented  by  clinical  and  pathological 
investigation,  to  trace  'ingoing'  impressions  from  their 
seats  of  origination  to  certain  portions  of  the  Cerebral 
Cortex :  the  regions  whence  Volitional  and  other  '  out- 
going '  stimuli  from  the  Cerebral  Cortex  were  given  off, 
were  also  indicated — so  far  as  they  are  at  present  known. 
Our  object  now  will  be  to  throw  some  little  light  upon 
the  extremely  complex  processes  which  have  been  super- 
added, or  that  have  grown  out  of,  the  processes  imme- 
diately excited  in  the  Cerebral  Cortex  by  the  incidence  of 
ingoing  impressions — and  as  a  result  of  which  outgoing 
stimuli  pass  over  to  motor  centres,  for  the  performance  of 
Voluntary  Acts  and  for  Intellectual  Expression  generally. 

We  shall  make  a  faint  attempt,  therefore,  to  begin  to 
unravel  the  order  of  the  incalculably  complex  intermediate 
processes  taking  place  in  the  highest  nerve  centre  of 
the  highest  animal  between  the  incidence  of  '  ingoing ' 
and  the  exit  of  '  outgoing  '  currents.  Such  actions  are  to 
be  regarded  as  elaborations  of  one  median  part  or  stage  of 
the  tj^pical  '  reflex  process,'  as  it  occurs  in  lower  organisms 
or  in  the  lower  nerve  centres  of  higher  organisms. 

Any  attempt  to  gauge  and  understand  the  Mental- 
processes  of  lower  animals  was  found  to  be  necessarily 
dependent  upon  the  study  of  their  Actions  under  par- 
ticular conditions.  Similarly,  our  attempts  to  gauge  and 
understand  the  Thought-processes  of  our  fellow-men, 
must  rest  ultimately  upon  a  study  of  their  Actions,  or  of 
the  results  of  their  actions,  as  embodied  in  Speech, 
Writing,  or  other  products  of  the  movements  which  they 
have  evoked  for  purposes  of  Intellectual  Expression.  In 
place  of  the  mere  emotional  signs  and  gestures  of  lower 
animals,  the  accumulated  results  of  the  movements 
employed    in   Speech    and  Writing   for   generation    after 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  615 

generation,  have  been  available  in  the  case  of  man  for 
the  building  up  of  that  great  department  of  human 
knowledge  known  as  Objective  Psychology. 

Our  aims  now,  however,  are  different  from  what  they 
were  in  the  earlier  chapters,  when  considering  the  mental 
processes  of  lower  animals.  We  were  then  principally 
concerned  with  the  endeavour  to  ascertain  something  as 
to  the  nature  of  these  mental  processes,  in  order  to 
learn  whether,  or  to  what  extent,  they  were  similar  to 
those  of  Man.  It  was  necessary  to  ascertain,  in  fact, 
whether  the  general  similarity  in  structure  of  their  Ner- 
vous System,  carried  with  it  a  general  similarity  in  mode 
of  action.  But  now  we  are  not  concerned  so  much  with 
the  estimation  of  the  nature  and  extent  of  Man's  mental 
2)ower3,  as  with  (a)  the  nature  and  order  of  the  processes 
involved  in  Thought  and  Intellectual  Expression  ;  and 
(h)  with  the  endeavour  to  refer  some  of  these  processes  to 
the  activity  of  definite  parts  of  the  Brain.  These,  in  fact, 
are  the  final  questions  needing  consideration,  in  order  to 
complete  our  necessarily  imperfect  sketch  of  what  is  at 
present  known  concerning  'the  Brain  as  an  organ  of  Mind.' 

In  the  first  of  these  analytical  studies  we  have  briefly 
to  consider  some  of  the  more  typical  of  the  various  defects 
in  Perception,  Verbal  Memory,  Thought,  and  Intellectual 
Expression  (either  by  Speech  or  Writing),  which  have 
been  observed  as  results  of  disease  or  injury  in  different 
parts  of  the  Cerebral  Hemispheres. 

The  great  importance  of  the  due  activity  of  tho 
Auditory  and  Visual  Preceptive  Centres,  and  the  absolute 
dependence  of  the  great  bulk  of  our  intellectual  percep- 
tions, of  our  memory  of  words,  and  of  our  powers  of 
thought,  as  well  as  of  intellectual  expression,  upon  the 
functional  integrity  and  proper  inter-action  of  these  parts 


616        THE  CEREBRAL  RELATIONS  OP 

may  have  been  gathered  by  the  reader  as  probabilities  from 
what  has  already  been  said  (see  also  p.  637,  footnote). 
These  conclusions  will  now,  however,  be  confirmed  by 
illustrations  drawn  from  the  histories  of  certain  carefully 
selected  examples  of  Brain-disease. 

It  must  continually  be  borne  in  mind  by  those  who 
study  these  examples,  that  each  Perceptive  Centre  is 
capable  of  being  called  into  activity  in  three  modes : — 
(1)  By  means  of  external  Impressions ;  (2)  by  '  Associa- 
tion ' — that  is,  by  impulses  communicated  from  another 
Centre,  during  some  act  of  Perception  or  during  some 
Thought-process ;  and  (3)  by  '  Voluntary '  recall  of  past 
impressions,  as  in  an  act  of  Recollection.* 

The  excitability  of  the  Centres — that  is,  the  molecular 
mobility  of  their  constituent  tissue-elements,  may  vary 
much  with  age,  state  of  health,  or  different  morbid  condi- 
tions. Their  mobility  may  be  so  much  loioered,  that  they 
are  only  capable  of  responding  to  powerful  stimuli ;  so  that 
whilst  '  Volitional '  recall  or  Recollection  may  be  impos- 
sible or  difficult  within  their  province,  they  may  still  be 
capable  of  acting  in  *  Association '  with  other  centres 
(that  is  in  an  automatic  manner  during  an  ordinary  pro- 
cess of  Thought),  and  still  more  easily  under  the  'sensory* 
stimulus  or  external  impression  which  is  the  forerunner  of 
a  Perceptive-process.  At  other  times,  the  excitability  of 
Perceptive  Centres  may  be  unduly  exalted,  so  as  to  lead 
to  hallucinations,  illusions,  and  a  wholly  different  class  of 
defects  often  met  with  among  Insane  persons,  but  which 
will  not  here  be  considered. 

Again,  the  Auditory  Word-Centres,  the  Visual  Word- 
Centres,  and  the  double  Kinesthetic  Word-Centres  (viz., 

*  These  second  and  third  modes  of  activity  are  probably  closely 
related  to  one  another,  though  we  have  no  definite  knowledge  con- 
cerning the  processes  involved  in  the  latter. 


Chap.  XXIX.J  SPEECH    AND    THOUGHT.  617 

those  in  relation  with  the  movements  for  Speech  and  for 
Writing)  are,  of  course,  only  parts,  though  probably  dis- 
tinct and  extensive  parts  of  the  respective  cerebral  Centres 
for  Audition,  Vision,  and  Kinaesthesis  generally.  Hence 
spoken  words  may  not  be  comprehended  though  other 
sounds  are ;  and  again,  written  or  printed  signs  may  not  be 
understood,  though  ordinary  objects  may  be  easily  recog- 
nized through  sight-impressions. 

Concerning  the  precise  functional  relations  of  thd 
Kinsesthetic  Word-Centres  with  the  corresponding  parts 
of  the  Visual  and  Auditory  Centres  nothing  is  at  present 
known — the  writer,  however,  believes  that  they  play  little 
or  no  part  in  Thought.  One  section  of  them  is  probably 
called  into  activity  principally  at  the  instigation  of  stimuli 
emanating  from  the  Auditory  Centre  for  the  bringing 
about  of  Articulate  Speech,  whilst  the  other  section  is 
probably  called  into  activity  principally  at  the  instigation 
of  stimuli  issuing  from  the  Visual  Centre  preliminary  to 
the  production  of  the  movements  concerned  in  Writing. 

From  this  point  of  view  the  Kinaesthetic  Centres  would 
be  concerned  more  with  the  expression  of  Thought  than 
with  the  Thinking-process  :  their  activity  would  only  be 
roused  as  Thought  is  about  to  translate  itself  into  Action. 
Thus,  they  may,  perhaps,  form  the  last  outposts  on  the 
side  of  '  ingoing '  currents,  and  be  at  the  same  time  the 
starting-points  for  *  outgoing  '  currents.  This  view  is  quite 
harmonious  with  the  fact  that  the  processes  taking  place 
therein  are  almost  as  devoid  of  conscious  accompaniment, 
and  almost  as  irrecoverable  in  idea,  as  are  the  molecular 
processes  occurring  in  the  Motor  Centres  upon  which  the 
initial  '  outgoing  '  currents  act. 

An  attentive  study  of  the  mental  defects  resulting  from 
Cerebral  Disease  will,  we  think,  be  found  to  yield  results 
quite  in  accordance  with  the  views  above  expressed. 


618  THE    CEREBRAL    RELATIONS    OF 

The  principal  defects  which  the  following  cases  are 
destined  to  illustrate,  may  with  advantage  be  first  tabu- 
lated, so  as  to  show  their  mutual  relations  both  as  Mental 
and  as  Neurological  Processes. 


I.    DEFECTS   OF  VERBAL  MEMOKY,    THAT    fS   DEFECTS   IN    THE     ASSOCIA- 
TIONS  OP   IDEAL    THINGS   OR   OF    CONCEPTIONS    WITH    IDEAL    WOIIDS. 

A.  Amnesia  Verbale. 

{a.  Paralytic  Variety ;  h.  Incoordinate  Variety.) 

1.  Diminished  Excitability  of  the  AHditorij  Word- Centres. 

2.  Defective  Action  in  the  Visual  Word-Centres. 

3.  Damage  to  Visual  Word-Centres  and  of  Afferent  Fibres  to  Audi' 

tory  Centres;  together  with  certain  defects  producing  IncO' 
ordinate  Amnesia. 

4.  Damage  to  Commissures  between  Auditory  and  Visual  Word- 

Centres. 

II.  DEFECTS  IN  THE  ASSOCIATION  OF  IDEAL  WOUDS  WITH  VERBAL 
MOVEMENTS  FOR  SPEECH  AND  WRITING,  OR  FOR  EITHER  OF  THEM 
SINGLE. 

B.  Aphasia. 

5.  Damage  to  first  2'> arts  of  outgoing  tracks  leading  from  Cerebral 

Word-Centres  to  left  Corpus  Striatum. 

C.  Agraphia. 

6.  Damage  to  first  parts  of  outgoing  trades  leading  from  the  left 

Visual  Word-Centre. 

D.  Aphemia. 

7.  Damage  (a)  to  first  farts  of  outgoing  track  leading  from  the  left 

Auditory  Word-Centre,  or  (b)  to  some  loiver  parts  of  the 
same  track,  or  (c)  to  the  actual  Motor  Centres  for  Articular 
tlon. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  619 


A.  Amnesia  Verb  ale.* 

In  the  acquirement  of  Speech  there  gradually  arises,  as 
-^e  have  seen,  an  '  association  '  between  the  impressions 
produced  by  external  objects,  as  well  as  between  the 
cerebral  processes  involved  in  ideas  and  other  mental 
states  on  the  one  side,  and  the  actual  or  revived  sounds 
or  sights  of  certain  Words  on  the  other.  A  similarly 
close  '  association  '  also  springs  up  between  these  latter 
processes  taking  place  in  the  Auditory  and  Visual  Per- 
ceptive Centres,  and  other  processes  in  Motor  Centres 
causative  of  Articulatory  Movements  for  the  production  of 
Sounds  corresponding  to  the  Names  of  the  objects  or  mental 
states  thought  of.  Thus  in  the  process  of  Thinking,  so 
long  as  the  brain  acts  in  a  healthy  manner,  Words  become 
nascent  in  consciousness  primarily,  and  perhaps  princi- 
pally, as  revived  Auditory  Impressions.  These  revived 
impressions,  either  without  or  with  voluntary  efforts  (that 
is,  by  Ideo-Motor  or  by  Voluntary  Action)  bring  about,  in 
a  manner  the  details  of  which  are  extremely  obscure, 
those  multiple  combinations  of  muscular  action  necessary 
for  the  Articulation  of  the  corresponding  Words.  If  this 
primary  memorial  association  between  the  impressions 
produced  by  things  and  their  names,  or  between  the  ideas 
of  things  and  other  mental  states  and  their  corresponding 
words,  prove  defective  (so  that  the  one  does  not  follow  the 

*  The  views  expressed  in  this  Chapter  were  contained  in  embr3''o 
in  a  paper  (pubHshed  in  1869,  in  the  "  Brit,  and  For.  Med.  Chir. 
Review")  entitled,  "On  the  Various  Forms  of  Loss  of  Speech  in 
Cerebral  Uisease."  The  present  Chapter  was  written  in  the 
aatiimn  of  1878,  and  therefore  contains  no  reference  to  recent 
communications.  The  author  has  since  read  Kussmaul's  elaborate 
article  (Ziemssen's  "  Cyclopaedia,"  vol.  xiv.)  where  many  of  the 
views  expressed  in  his  earlier  papers  are  endorsed. 


620        THE  CEREBRAL  RELATIONS  OF 

other  immediately)  it  seems  evident  that,  in  proportion  to 
the  degree  of  these  particular  defects,  there  must  be  a 
diminution  in  the  power  of  Speaking,  and  a  hinderance, 
though  to  a  less  extent,  in  the  process  of  Thinking. 

Two  kinds  of  defective  Verbal  Memory  require  to  be 
distinguished.*  One  of  them  is  dependent  upon  a  dimin- 
ished activity  in  one  or  other  of  the  parts  of  the  Brain 
concerned  with  the  verbal  associations  above  referred  to. 
Such  diminution  may  amount  to  a  more  or  less  complete 
arrest  of  action  or  paralysis,  hence  this  variety  may  be 
named  Paralytic  Amnesia.  The  other  kind  of  defect  is 
related  to  an  irregular  or  'perverted  activitij  of  the  parts 
in  question.  They  act,  but  they  act  wrongly.  It  is  not 
that  words  cannot  be  revived,  but  rather  that  Avrong  words 
are  revived,  just  as  an  '  ataxic '  man  produces  wrong 
movements  of  his  limbs.  This  second  variety  may,  there- 
fore, fitly  enough  be  distinguished  as  Incoordinate  Am- 
nesia. Though  the  two  conditions  may  exist  separately, 
they  are  often  combined  in  different  proportions, 

a.  Paralytic  Amnesia. 

Under  this  head  may  be  included  a  momentary  forget- 
fulness  and  confusion  about  proper  Names  and  Nouns, 
with  power  of  recovery  after  a  time  ;  or  there  may  be  a 
more  permanent  and  habitual  forgetfulness  of  Names  of 
objects,  persons,  or  places,  with  attempts  to  remedy  this 
forgetfulness  by  employing  a  periphrasis  in  place  of  the 
Noun,  which  cannot  be  recalled. 

Different  degrees  and  special  varieties  of  this  kind  of 
defect  are  recorded  in  the  following  sections. 

*  In  reference  to  Memory  generally,  some  very  suggestive  and 
original  views  may  be  found  in  a  paper  by  the  late  Dr.  Laycock,  in 
'•  Edin.  Med.  Jrnl.,"  April,  1874. 


CuAP.  XXIX.]  SPEECH    AND    THOUGHT.  621 

3. —  Diminished    Excitahility    of    the    Auditory    Word- 
Centres. 

According  to  the  degree  in  which  the  proper  vitality 
of  the  Auditory  Word- Centres  is  affected,  we  may  find 
evidence  that  they  ceaso  to  respond,  first  to  '  vohtional  * 
incitations,  secondly  to  those  coming  to  them  hy  way  of 
*  association,'  and  lastly  to  '  sensory '  impressions  coming 
from  without. 

A  good  example  of  an  ordinary  case  of  Amnesia  is 
thus  referred  to  hy  Trousseau  in  his  "  Lectures,"  in  which 
the  'volitional'  and  '  associational '  recall  of  names  was 
impossible,  though  their  '  sensory '  recall  was  preserved. 

"  The  patient  does  not  speak,  because  he  does  not  remember  the 
words  which  express  ideas.  You  recollect  the  experiment  which  I 
often  repeated  at  Marcou's  bed-side.*  I  placed  his  nightcap  on  his 
bed,  and  asked  him  what  it  was.  But  after  looking  at  it  atten- 
tively he  could  not  say  what  it  was  called,  and  exclaimed,  'And 
yet  I  know  well  what  it  is,  but  I  cannot  recollect.'  When  told 
that  it  was  a  nightcap,  he  replied,  '  Oh !  yes,  it  is  a  nightcap.* 
The  same  scene  was  repeated  when  various  other  objects  were 
shown  to  him.  Some  things,  however,  he  named  well,  such  as  his 
pij^e.  He  was,  as  you  know,  a  navvy  ;  and,  therefore,  worked 
chiefly  with  the  shovel  and  the  pickaxe,  so  that  these  are  objects 
the  names  of  which  a  navvy  should  not  forget.  But  Marcou  could 
never  tell  us  what  tools  he  worked  with,  and  after  he  had  been 
vainly  trying  to  remember,  when  I  told  him  it  was  with  the  shovel 
and  the  pickaxe, '  Oh !  yes,  it  is,'  he  would  reply,  and  two  minutes 
afterwards  he  was  as  incapable  of  naming  them  as  before." 

In  the  slighter  forms  of  Amnesia  the  efforts  at  Eecol- 
lection  of  a  person  who  is  ''  at  a  loss  for  a  word  "  tend 
also  to  call  the  Visual  Word- Centres  into  an  incipient  or 

*  The  earlier  condition  of  this  man  will  hereafter  be  referred  to 
(p.  627),    as   at   that  time   he  manifested    a  distinct  tendency  to 
echo  '  words. 


622  THE    CEREBRAL    RELATIONS    OF 

abortive  amount  of  activity.  Dr.  Graves  has  placed  on 
record  what  may  be  taken  as  an  illustration  of  this  fact, 
though  he  quotes  the  case  merely  as  **a  remarkably  exag- 
gerated degree  of  the  common  defect  of  memory  observed 
in  the  diseases  of  old  age,  in  which  the  names  of  persons 
and  things  are  frequently  forgotten,  although  their  initials 
are  recollected.''* 

"  A  farmer,  fifty  years  ago,  had  suffered  from  a  paralytic  attack, 
from  which  he  had  not  recovered  at  the  time  of  observation.  The 
attack  was  succeeded  by  a  painful  hesitation  of  speech.  His 
memory  was  good  for  all  parts  of  speech  except  noun- suhstant Ives 
and  proper  names :  the  latter  he  could  not  at  all  retain.  This 
defect  was  accompanied  by  the  following  singular  peculiarity : — he 
perfectly  recollected  the  initial  letter  of  every  substantive  or  proper 
name  for  which  he  had  occasion  in  conversation,  though  he  could 
not  recall  to  his  memory  the  word  itself.  Experience  had  taught 
him  the  utility  of  having  written  on  manuscript  a  list  of  the 
things  he  was  in  the  habit  of  calling  for  or  speaking  about,  in- 
cluding the  proper  names  of  his  children,  servants,  and  acquain- 
tances ;  all  these  he  arranged  alphabetically  in  a  little  pocket 
dictionary,  which  he  used  as  follows: — if  he  wished  to  ask  any- 
thing about  a  cow,  before  he  commenced  the  sentence  he  turned  to 
the  letter  C,  and  looked  out  for  the  word  *  cow,'  and  kept  his  finger 
and  eye  fixed  on  the  word  until  he  had  finished  the  sentence.  He 
could  pronounce  the  word  '  cow  '  in  its  proper  place  so  long  as  he 
had  his  eyes  fixed  upon  the  written  letters ;  hut  the  moment  he  shut 
his  booh  it  passed  out  of  Ms  memory  and  could  not  he  recalled, 
although  he  recollected  its  initial,  and  could  refer  to  it  ivhen  neces- 
sary. He  could  not  even  recollect  his  own  name  unless  he  looked 
out  for  it,  nor  the  name  of  any  person  of  his  acquaintance;  but 
he  never  was  at  a  loss  for  the  initial  of  the  word  he  wished  to 
employ." 

In  regard  to  this  memory  of  the  first  letter  alone  of  a 
Name  or  Word,  the  following  passage  from  David  Hartley 
is  not  without  interest.  He  said,'*^  whilst  illustrating  his 
celebrated  doctrine  of  'Association  '  : — "When  a  variety 

*  "  Observations  on  Man,"  1748,  Prop,  xii.,  Cor.  vii. 


CiiAi.  XXIX.]  SPEECH    AND    THOUGHT.  623 

of  ideas  are  associated  together,  the  visible  idea,  being 
more  glaring  and  distinct  than  the  rest,  performs  the 
office  of  a  symbol  to  all  the  rest,  suggests  them  and 
connects  them  together.  In  this  it  somewhat  resembles 
the  first  letter  of  a  word,  or  first  word  of  a  sentence, 
which  are  often  made  use  of  to  bring  all  the  rest  to 
mind."  The  fact,  moreover,  that  in  these  cases — when 
we  cannot  '  get  out '  a  particular  word — we  often  seem  to 
know  something  of  its  length,  and  can  say  that  it  consists 
of  about  so  many  letters,  also  seems  to  testify  to  an 
abortive  or  incipient  revival  of  the  Word  in  the  Visual 
Centre. 

The  fact  that  this  partial  Visual  revival  is  not  asso- 
ciated with  full  consciousness  of  the  word  and  does  not 
enable  it  to  be  Written,  is  one  of  considerable  significance, 
because  it  seems  to  show  how  all-important,  in  the  majority 
of  cases,  is  the  primary  revival  in  the  Auditory  Centres,  not 
only  for  the  accomplishment  of  Speech  but  also  for  that  of 
Waiting ;  and,  further,  that  the  more  special  Intellectual 
or  Emotional  Mechanisms,  often  cannot  immediately  rouse 
the  Visual  Word-Centres  for  the  execution  of  Writing 
Movements,  these  being  probably  called  into  play,  in 
Writing  spontaneously  as  well  as  in  Writing  from  dicta- 
tion, for  the  most  part  through  the  intermediation  of  the 
Auditory  Word-Centres. 

A  remarkable  kind  of  defect,  of  an  exceptional  order 
and  very  difficult  of  explanation,  has  been  recorded  by 
Dr.  Hertz,  who  says  {''  Psycholog.  Mag.,"  vol.  viii.)  : — 

"  In  August,  1785,  I  was  called  to  an  officer  of  artillery,  a  man 
about  forty  years  old,  who,  as  I  was  informed,  was  seized  with  a 
palsy I  found  him  so  much  recovered  as  to  have  the  com- 
plete use  of  his  feet;  his  hands  also  were  stronger,  but  in  regard  to 
his  speech  the  following  very  remarkable  circumstance  was  to  be 
observed :  he  was   able  to  articulate  distinctly  any  words  which 


624  THE    CEREBRAL    RELATIONS    OF 

either  occurred  to  him  s^pontaneously,  or  when  they  were  slowly  and 
loudly  repeated  to  him.  He  strenuously  exerted  himself  to  speak, 
but  an  unintelligible  kind  of  murmur  was  all  that  could  be  heard. 
The  effort  he  made  was  violent,  and  terminated  in  a  deep  sigh.  On 
the  other  hand,  he  could  read  aloud  with  facility.  If  a  book  or 
any  written  paper  were  held  before  his  eyes,  he  read  so  quickly 
and  distinctly  that  it  was  impossible  to  observe  that  there  was  the 
slightest  fault  in  his  organs  of  speech.  But  if  the  book  or  paper 
were  withdrawn  he  was  then  totally  incapable  of  pronouncing  one 
of  the  words  which  he  had  read  the  instant  before.  I  tried  this 
experiment  with  him  repeatedly,  not  only  in  the  presence  of  his 
wife,  but  of  many  other  people:  the  effect  was  uniformly  the 
same." 

Here  it  would  appear  that  Words  could  not  properly  be 
revived  in  the  Auditory  Centres  by  '  volitional '  incitations, 
and,  consequently,  that  '  outgoing '  stimuli  could  not  be 
made  to  pass  over  from  them  to  the  motor  centres  con- 
cerned in  Speech.  His  difficulty  in  repeating  words 
(implying  sluggishness  of  response  of  the  Auditory  Word- 
Centre  to  direct  '  sensory '  impressions)  makes  this  case 
Lard  to  understand.  The  view  that  the  molecular  mobility 
of  tins  Centre  itself  was  lowered,  or  that  its  emissive  fibres 
were  damaged,  is  not  in  accord  with  the  fact  that  it  ap- 
peared still  to  respond  well  to  strong  impulses  coming  to 
it  from  the  Visual  Centre.  And  evidence  will  subsequently 
be  given,  tending  to  show  that  in  '  reading  aloud '  the 
Auditory  Word-Centre  is  called  into  play,  so  that  it 
then  acts  as  in  ordinary  Speech  (p.  G41).  But  there  may 
be  exceptions  to  this  rule.  Both  this  case  and  the  one 
which  follows  would  be  more  explicable  if  we  might  sup- 
pose that  motor  incitations  could,  in  some  well  practised 
persons,  pass  over,  in  Beading,  from  the  Visual  Word- 
Centre  to  the  portions  of  the  Kinesthetic  Word-Centre 
in  association  Avith  Speech-movements,  without  previously 
passing  through  the  Auditory  Word-Centre.  By  analogy 
it    would    seem    quite    possible    that    this     may    occur, 


Chap.  XXFX.]  SPEECH    AND    THOUGHT.  625 

just  as  the  initiallj-guiding  Visual  Sense  may  after  a  time 
be  dispensed  with  in  the  execution  ol  ordinary  movements 
(p.  556). 

The  next  case*  is  rather  more  comphcated,  but  it  affords 
clearer  evidence  of  a  great  diminution  in  the  excitability 
of  the  Auditory  Word- Centre. 

Dr.  Hun,  of  Albany,  mentions  the  case  of  a  blacksmith,  set.  35, 
who,  before  the  present  attack,  could  read  and  write  with  facility. 
He  had  been  labouring  for  several  years  under  disease  of  the 
heart.  After  a  long  walk  in  the  sun  he  was  seized  one  evening 
with  symptoms  of  cerebral  congestion,  and  remained  in  a  state  of 
stupor  for  several  days.  On  recovering  from  this  condition  he 
understood  what  was  said,  but  it  was  observed  that  he  had  great 
difficulty  in  expressing  himself  in  words,  and  for  the  most  part 
CDuld  only  make  his  wants  known  by  signs.  There  was  no  para- 
lysis of  the  tongue,  which  he  could  move  in  all  directions.  H^  knew 
the  meaning  of  words  spoken  before  Mm,  hut  could  not  recall  those 
needed  to  express  himself,  nor  could  he  repeat  words  when  he  heard 
them  pronounced ;  he  was  conscious  of  the  difficulty  under  which 
he  was  labouring,  and  seemed  surprised  and  distressed  at  it.  If 
Dr.  Hun  pronounced  the  word  he  needed,  he  seemed  pleased,  and 
would  say,  "Yes,  that  is  it,"  but  was  unable  to  repeat  the  words 
after  him.  After  fruitless  attempts  to  repeat  a  word,  Dr.  Hun 
wrote  it  for  him,  and  then  he  would  begin  to  spell  it  letter  by  letter, 
and  after  a  few  trials  was  able  to  pronounce  it ;  if  the  writing  were 
now  taken  from  him  he  could  no  longer  pronounce  the  word;  but 
after  a  long  study  of  the  written  word,  and  frequent  repetition,  he 
would  learn  it  so  as  to  retain  it,  and  afterwards  use  it.  He  kept  a 
slate,  on  which  the  words  he  required  most  were  written,  and  to 
this  he  referred  when  he  wished  to  express  himself.  He  gradually 
learned  these  words  and  extended  his  vocabulary,  so  that  after  a 
time  he  was  able  to  dispense  with  his  slate.  He  could  read  tolerahly 
well  from  a  sprinted  hook,  hut  hesitated  ahout  some  words.  When 
he  was  unahle  to  pronounce  a  word  he  was  also  unahle  to  write  it 
till  he  had  seen  it  ivritten ;  and  then  he  could  learn  to  write  as  he 
learned  to  pronounce,  by  repeated  trials.  At  the  end  of  six  months 
by  continually  learning  new  words,  he  could  make  himself  under- 

*  American  "  Jrnl.  of  Insanity,"  Ap.  1851;  and  given,  as  here, 
in  abstract  by  Dr.  Bateman  in  "  Jrnl.  of  Ment.  Sc,"  Ap.  18G8. 


626  THE    CEREBRAL    RELATIONS    OF 

Btood  pretty  well,  often,  however,  employing  circumlocution  w\ien 
lie  could  not  recall  the  proper  word,  somewhat  as  if  he  were  speak- 
ing a  foreign  language  imperfectly  learned." 

The  fact  that  Words  could  not  be  articulated  which 
had  just  been  pronounced  before  him,  though  such  Words 
were  really  heard  and  understood,  seems  to  point  to  a 
very  low  degree  of  activity  of  the  Auditory  Word- Centre. 
The  patient's  ability  to  read  aloud,  however,  as  in  the  last 
case,  appears  to  make  it  probable  that  this  act  may  be  per- 
formed, as  previously  explained,  without  necessarily  involv- 
ing the  activity  of  the  Auditory  Word- Centres.  The  fact 
that  this  person  had  a  difficulty  not  only  in  pronouncing 
certain  words  from  sight,  but  in  writing  them,  seemed  to 
point  to  the  existence  of  some  small  amount  of  functional 
impairment  in  the  Visual  Word- Centre. 

In  this  relation  it  may  be  mentioned  that  in  different 
kinds  of  Cerebral  Disease  it  sometimes  happens  that  the 
patients'  Speech  is  entirely  limited  to  a  mere  imitative 
repetition  of  words  spoken  in  their  hearing,  whilst  they 
are  without  the  power  of  volunteering  any  statement — i.e, 
their  Auditory  Word-Centres  respond  only  to  direct  '  sen- 
sory *  incitations,  and  not  at  all  to  those  of  the  *  associa- 
tional'  or  *  volitional'  types.  In  these  cases,  other  causes 
of  general  mental  impairment  almost  invariably  co-exist. 

A  defect  of  this  kind  (occurring  in  a  woman  who  was  hemiplegio 
from  cerebral  haemorrhage)  has  been  recorded  hy  Professor  Behier.* 
She  was  horn  in  Italy,  and  had  resided  hoth  in  Spain  and  France; 
of  the  three  languages  she  had  thus  acquired  she  had  coni23letely 
forgotten  the  Italian  and  Spanish,  and  had  only  retained  a  most 
limited  use  of  French.  In  this  latter  language  ehe  only  repeated 
like  an  echo  the  words  pronounced  in  her  presence,  without,  how- 
ever, attaching  any  meaning  to  them.  But  in  the  case  of  a  woman 
seen  at  the  Salpetricre  hy  Bateman  the  mimetic  tendency  was 
much  stronger.     She  even  reproduced  foreign  words  with  which 

♦  "  Gaz.  des  llopitaux,"  May  16,  1867. 


Crap.  XXIX.]  SPEF.CH    AND    THOUGHT.  627 

she  had  never  been  familiar.  "  In  the  words  that  she  thus  ecJioedf 
her  articulation  was  distinct,  although  the  foreign  phrases  were  not 

repeated  in  quite  so  intelligible  a  manner  as  the  French Just 

as  we  were  leaving  her  bedside,  a  patient  in  an  adjoining  bed 
coughed ;  the  cough  was  instantly  imitated  by  this  human  parrot ! 
In  fact,  this  singular  old  woman  repeated  everything  that  was 
said  to  her,  whether  in  an  interrogative  form  or  not;  and  she 
imitated  every  act  that  was  done  before  her,  and  that  with  the 
most  extraordinary  exactitude."  In  other  cases  there  is  a  tendency 
to  dwell  upon  and  repeat  some  one  word  or  phrase  that  has  been 
uttered  in  reply  to  a  first  question,  as  an  answer  to  those  which 
follow — till  at  last  something  new  may  be  said  which  is  repeated  in 
the  same  way.  A  good  instance  of  this  may  be  quoted  from 
Trousseau.  In  a  man  suffering  from  left  hemiplegia,  his  usual 
"  stock  of  words  was  restricted  to  these  two,  '  My  faith  ! ' ;  and 
when  he  was  pressed  hard,  he  looked  impatient,  and  uttered  the 

oath, '  Ore  nom  d'un  Coeur ! ' I  asked  him  what  his  name 

was,  and  his  occupation ;  he  looked  at  me  and  answered  :  '  My 
faith !'....  I  insisted,  but  in  spite  of  his  efforts,  he  only  shook 
his  head  with  an  impatient  gesture,  exclaiming :  '  Ore  nom  d'un 
Coeur.'  As  I  wished  to  find  out  how  many  words  he  had  at  com- 
mand, I  said  to  him :  '  Are  you  from  the  Haute-Loire  ? '  He 
repeated  like  an  echo,  'Haute-Loire!'  'What's  your  name?  ' — 
*  Haute-Loire.'  *  Your  profession  ?  ' — '  Haute-Loire.'  '  But  your 
name  is  Marcou  ? ' — '  Yes,  sir.'  *  You  are  sure  it  is  Marcou  ?  ' — 
*Yes.'  'What  department  do  you  come  from?' — 'Marcou.' 
•No;  that's  your  name.'  But  with  an  impatient  gesture,  he  ex- 
claimed, '  Ore  nom  d'un  Coeur.'  '*  * 


2. — Defective  Action  in  the  Visual  Word-Centres. 

No  very  distinct  illustration  of  this  defect  has  been 
met  with,  but  one  which  is  in  some  respects  the  converse 
of  those  recorded  by  Drs.  Hertz  and  Hun  has  been  re- 
lated by  Dr.  Hughlings  Jackson. f     In  this  example  the 

*  The  same  kind  of  tendency  to  repeat  the  last  impression  mado 
on  the  Yisual  Centre  is  shown  by  other  patients,  when  Writing 
(see  Trousseau's  "  Lectures,"  Eng.  Trans.,  Pt.  I.  p.  228). 

t  "Brit.  Med.  Journ.,"  1866. 


628  THE    CEREBRAL    RELATIONS    OP 

power  of  Writing  and  of  Spelling  was  very  much  impaired, 
whilst  that  of  Speech  was  affected  only  to  a  more  trifling 
extent. 

The  man  had  "  performed  the  duties  of  an  important  government 
office,  requiring  good  education  and  intelligence,"  and  he  had  been 
subject  to  a  series  of  epileptiform  attacks,  at  first  principally 
involving  the  left  side  of  the  body,  but  then,  after  an  interval, 
affecting  the  right  side  instead.  The  defects  in  the  patient'a 
power  of  intellectual  expression  about  to  be  noted  occurred  only 
after  the  second  series  of  fits.  Dr.  Jackson  says,  "  After  these 
attacks,  the  patient  could  talk,  but  he  made  mistakes  in  talking." 
A  few  weeks  afterwards,  he  met  this  patient  in  the  street,  and  says, — 
•*  He  was  then,  to  superficial  appearance,  as  well  as  ever.  I  oh- 
eerved  that  he  spohe  quite  well,  and  this  throughout  rather  a  lonrj 
conversation.  The  patient  said,  however,  that  he  was  oflen  at  a 
loss  for  a  word ;  and  his  father  told  me  that  his  son  frequently 
made  mistakes  in  names."  His  greatest  trouble  was  in  writing — 
he  had  no  difficulty  about  the  mere  penmanship,  this  was  excellent. 
*'  His  trouble  was  that  he  could  not  readily  find  the  proper  words, 
and  those  he  wrote  he  often  spelled  incorrectly."  He  v/^as  able  to 
copy  a  paragraph  from  a  printed  book  well,  making  only  one  or 
two  trivial  errors;  but  in  attempting  to  write  from  dictation,  he 
made  very  much  worse  mistakes  in  spelling  than  occur  in  a  cor- 
rected letter  which  Dr.  Jackson  has  reproduced.  When  asked  to 
spell  words,  he  also  succeeded  very  badly ;  and  though  he  could 
repeat  iderfecthj  even  the  most  difficult  sentences,  luhen  he  attempted 
to  read  aloud  he  could,  not  succeed  at  all,  pronouncing  almost  evertj 
word  of  tivo  or  more  syllahles  wrongly. 

Here,  again,  as  in  the  case  recorded  by  Dr.  Hun  (p.  C23), 
the  ability  to  read  aloud  was  commensurate  rather  with 
the  power  of  writing  than  with  that  of  speaking.  Both 
reading  aloud  and  writing  necessarily  require  the  integrity 
of  the  Visual  Centre,  and  that  this  was  more  impaired 
than  the  Auditory  Centre  seems  clearly  indicated  by  the 
fact  recorded  above,  that  the  patient  could  repeat  even 
the  most  difficult  sentences  correctly — an  operation  in 
which  the  Auditory  Word-Centres  are  called  into  play,  but 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  629 

not  the  Visual — whilst  he  could  not  read  aloud  the  simplest 
passage  without  making  many  mistakes.  It  will  be  inte- 
resting subsequently  to  compare  these  cases  with  those 
that  will  be  given  under  the  head  of  Agraphia  (p.  657), 
especially  the  other  case  recorded  by  Dr.  Jackson,  which 
might  perhaps  with  equal  propriety  be  placed  here. 


3. — Damage  to  Visual  Word-Centre,  and  of  Afferent 
Fibres  to  Auditory  Centres ;  together  ivith  certain  defects 
'producing  Incoordinate  Amnesia* 

A  case  of  great  interest  belonging  to  this  category  has 
been  fully  recorded  by  Dr.  Banks, f  but  is  given  here  only 
in  abstract.  The  power  of  apprehending  what  was  spoken 
by  others  was  entirely  lost,  and  the  patient's  ability  to 
comprehend  written  or  printed  characters  was  almost 
lost.  His  powders  of  expression  by  Speech  and  Writing 
were  correspondingly  defective.  He  seemed  to  have  lost 
all  knowledge  of  the  proper  use  of  Words,  and  was  unable 
to  express  himself  in  an  intelligible  manner. 


A  gentleman,  aged  about  seventy- five,  after  having  walked  a 
considerable  distance  on  the  28th  of  March,  1864,  sat  down  to 
dinner,  and  proceeded  with  his  meal  as  usual.  After  a  time  it  was 
observed  that  some  of  the  water  he  was  drinking  flowed  from  his 
mouth.  He  put  down  the  glass,  calling  at  the  same  time  in  a  loud 
and  excited  voice  for  his  wife  and  the  servant  who  was  in  the  habit 
of  waiting  upon  him,  although  they  were  both  present.  The  patient 
was  in  a  very  short  time  seen  by  Dr  Kidd,  who  found  him  sitting 
on  the  sofa,  looking  puzzled  but  evidently  conscious,  calling  out 
loudly  at  intervals  for  the  servant  and  others,  but  not  taking  the 
slightest  notice  of  anything  which  was  said  to  him.     The  excite- 

■*  The  consideration  of  the  nature  of  the  defects  inducing  this 
latter  condition,  will  be  better  deferred  till  some  examples  of  the 
condition  itself  have  been  given. 

f  "Dublin  Quart.  Jrnl.  of  Med.  Science,"  Feb.  1865,  p.  78. 


630  THE    CEREBRAL    RELATION'S    OF 

tnent  under  which  he  laboured  after  a  time  passed  away.  He 
endeavoured  to  speak,  but  unintellicribly.  He  walked  upstairs  un- 
assisted, wound  up  his  watch,  went  to  bed,  and  slept  well.  The 
following  morning  it  was  discovered  that  he  was  completely  deof,  the 
loudest  noises  not  being  perceived.  His  sight  seemed  good,  and  there 
was  no  motor  paralysis  of  any  kind.  In  speaking  he  used  wrong 
words,  so  as  to  be  utterly  unintelligible.  Dr.  Banks  says,  "  he  cer- 
tainly recognized  me,  and  was  glad  to  see  me,  but  misnamed  me; 
saying  something,  but  using  words  without  meaning.  We  endea- 
louredto  communicate  with  him  by  writing,  but  it  was  evident  that 
he  did  not  understand  it.  '  Have  you  pain  ?  '  was  written,  and  he 
looked  at  it  and  said,  '  Good,  good  God;'  appearing  to  read  what 
was  written."  He  attempted  to  write  letters  frequently,  and  his 
address  was  written  two  or  three  times  at  the  head  of  the  sheet 
of  paper,  some  of  the  words  being  imperfect.  '  My  dear  Sir,'  was 
written  correctly.  The  sheet  was  filled^  with  writing,  but  no  word 
except  'tvife'  was  legible,  the  rest  being  utterly  meaningless ;  some 
letters  were  correctly  formed,  but  no  ivords  until  the  end,  where  his 
name  was  signed  with  a  steady  hand  and  in  his  usual  manner. 
He  varied,  however,  in  his  power  of  writing  at  different  times; 
occasionally  when  wished  to  sign  his  name,  he  could  not  be  induced 
to  do  so,  and  "  only  scribbled  some  unintelligible  words."  It  was 
imi)Ossible  to  get  him  to  understand  anything ;  and  his  meaning 
could  only  be  guessed  at  by  his  gestures,  and  by  the  very  few 
words  at  his  command,  which  were  almost  always  misapplied. 

At  the  beginning  of  April  a  remittance  was  due  from  his  agent, 
and  each  morning  he  was  much  excited,  asking  frequently  for 
something.  At  length  it  occurred  to  one  of  the  family  to  show 
him  his  agent's  letter,  which  seemed  to  please  him  ;  but  he  was  not 
quite  satisfied  till  the  money  was  brought  and  counted  before  him. 
Some  shillings  were  not  shown  to  him  at  first,  but  when  he  saw 
them  he  appeared  to  know  all  was  right,  and,  on  the  money  being 
handed  to  his  wife,  he  seemed  content.  His  feelings  of  affec- 
tion for  his  wife  seemed  to  be  intensified;  but  there  was  some 
amount  of  emotional  weakness. 

He  occasionally  for  a  time  made  use  of  some  one  word,  applying 
it  in  the  most  varied  ways.  Wishing  to  inform  Dr.  Kidd  that  a 
Kniment  which  he  had  been  using  was  nearly  finished,  he  said, 
pointing  to  the  bottle,  *'  Bring  the  cord."  On  another  occasion, 
speaking  of  pills  he  had  been  taking,  he  said  he  had  taken 
"potatoes.*'      Very  frequently  there  was  some   similarity  in  the 


CuAP.  XXIX.]  SPEECH    AND    THOUGHT.  631 

word  used  to  the  right  one ;  or  it  could  be  discerned  that  there  was 
Bome  association  with  the  idea  he  wished  to  convey ;  for  example, 
giving  his  waistcoat  to  be  put  aside,  the  watch  being  in  his  pocket, 
he  said — **  Take  care  of  the  break-fall."  He  seemed  conscious  of 
his  deafness,  and  sometimes  spoke  of  it.  One  day  he  said  he  could 
neither  hear  nor  read — "  Only  a  little,  could  read  the  words,  hut 
could  not  take  in  the  meaning.'*  Every  morning,  notwithstanding, 
he  spent  some  time  as  if  busily  engaged  reading  the  Bible  and  the 
newspapers.  This  was,  doubtless,  from  the  mere  force  of  habit ; 
for  on  testing  him,  he  read  after  a  fashion,  but  the  words  were 
unconnected  and  meaningless,  and  had  not  even  the  most  remote 
connection  with  the  text.  His  powers,  both  of  speaking  and  writ- 
ing, were  subject  to  variation  at  different  times.  (Lithographs  of 
two  letters  are  given  by  Dr.  Banks  which,  though  made  up  of 
properly  written  words,  are  almost  unintelligible.)  Occasionally 
it  was  difficult  to  manage  him ;  as,  if  he  wished  to  go  somewhere, 
and  it  was  found  impossible  to  comprehend  his  wishes,  he  became 
very  much  excited.  He  continued  in  much  the  same  condition 
till  the  7th  of  October,  when  he  had  a  distinct  apoplectic  seizure, 
and  became  completely  hemiplegic  on  the  right  side  of  the  body. 
He  lived  only  a  week  after  the  onset  of  this  more  severe 
attack. 

The  great  mental  defects  in  this  case  were  unassociated 
with  paralysis.  The  Visual  Centre  was  evidently  much 
damaged,  since  the  patient  could  not  understand  printed 
or  written  characters  and  could  only  write  in  an  unintel- 
ligible manner.  This  same  conclusion  is  strengthened  by 
the  fact  that  he  read  so  badly — even  worse  than  he  spoke. 
His  amnesic  defects  of  speech,  of  the  incoordinate  type, 
were  probably  due  to  some  lack  of  harmony  between  the 
higher  Intellectual  and  the  Auditory  Centres,  but  this 
subject  will  presently  be  considered  more  at  length.  His 
total  deafness,  coupled  with  his  ability  to  articulate  fairh^ 
well,  seemed  incompatible  with  the  existence  of  a  grave 
lesion  of  the  Auditory  Centre  itself.  The  fact,  how- 
ever, of  the  existence  of  this  complete  deafness  is  an 
exceptional  feature,  difficult  to  explain  on  the  otherwise 


632  THE    CEREBRAL    RELATIONS    OF 

probable  supposition  that  originally  only  one  seat  of 
disease  existed  in  the  Cerebral  Cortex.  If  ordinary  right- 
sided  deafness  had  existed  anterior  to  the  date  of  this 
patient's  sudden  cerebral  disease,  his  symptoms  might  be 
explained  by  one  lesion  of  or  near  the  Cortex  of  the  left 
Hemisphere,  seriously  damaging  the  afferent  fibres  going 
to  the  Auditory  Centre,  as  well  as  seriously  deranging  the 
functional  activity  of  the  corresponding  Visual  Centre. 

Dr.  Broadbent*  has  recorded  a  clinical  history  in  many 
respects  comparable  with  the  foregoing. 

A  painter,  £et.  42,  had  been  subject  to  gout,  and  also  to  epilepti- 
form attacks,  for  several  years.  During  the  night  of  October  14, 
1871,  while  lying  on  the  right  side,  he  suddenly  put  out  the  left 
arm  and  began  to  jabber — his  right  arm  being  quite  useless.  There 
were  no  convulsions,  and  no  loss  of  consciousness.  He  was  found 
by  Dr.  Felce,  who  was  called  to  him,  completely  hemiplegic  and  with 
greatly  impaired  sensibility  of  his  right  side,  keeping  up  a  mean- 
ingless gabble,  in  which  m-sounds  were  predominant,  and  show- 
ing the  paralyzed  arm.  The  attack  was  followed  by  much  cerebral 
excitement,  shouting  and  violence.  He  soon  regained  power  in 
the  right  limbs,  but  the  speech  was  as  imperfect  as  ever,  and  he 
was  unable  to  write  or  copy.  His  general  health  became  much 
deranged,  and  finally  gangrene  of  the  left  foot  came  on.  It  was 
soon  after  this,  on  Dec.  14,  that  he  was  first  seen  by  Dr.  Broad- 
bent,  who  says  : — "  He  received  us  with  a  profusion  of  bows  and 
smiles,  with  gestures  expressive  of  welcome  ....  His  speech 
was  a  mere  jabber,  in  which  'Ma'  and  '  IMura '  were  prominent, 
and  was  accompanied  with  an  excess  of  gesticulation,  smiles,  and 
facial  expression.  The  gestures  were  very  striking,  and  apparently 
appropriate  when  we  had  a  key  to  their  meaning  ....  It 
was  stated  that  he  said  *  Yes  '  or  *  No,'  and  '  Oh,  my  '  at  times ; 
but  he  did  not  use  even  these  simple  words  before  us.  He  was 
unable  to  write  his  own  name  when  his  signature  was  before  him. 
When  urged  to  do  so,  he  scribbled  of  o-apldly  something  in  ivhich 
letters  of  some  sort  were  distinguishable  at  first,  but  then  tailing  off 
into  a  scraiul." 

"  He  obviously  did  not  understand  anything  that  was  said  to  him; 

♦  "Medico-Chirug.  Transact.,  1872,"  p.  170. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  633 

did  not  squeeze  my  hand  on  rei:»ealed  requests,  but  went  on  shak- 
ing it  and  smiling  ;  put  out  his  tongue  repeatedly  when  told  to  close 
his  eyes,  but  instantly  imitated  the  act  after  Dr.  Felce.  It  vjas 
douhtful  how  far  he  recognized  the  state  of  his  speech ;  he  went  on 
cliattering  as  if  he  thought  he  was  understood,  but  he  also  mado 
signs  ....  He  remained  in  much  the  same  state  till  his  death, 
about  Christmas ;  once  startling  some  friends  in  conversation  at 
his  bedside  by  exclaiming  'Exactly  '  at  a  very  appropriate  moment, 
but  not  otherwise  regaining  speech." 

In  this  case,  whilst  the  damage  to  the  left  Visual  Word- 
Centre  was  probably  even  greater  than  that  recorded  by 
Dr.  Banks,  the  left  Auditory  Word-Centre  seems  to  have 
been  equally  damaged,  as  was  shown  by  the  patient  being 
unable  to  articulate  distinct  words,  combined  with  his 
seeming  inability  to  understand  spoken  language.*  In 
another  case,  recorded  by  Dr.  Broadbent,  there  was  the 
same  inability  to  understand  what  was  said,  although  this 
patient  w^as  accustomed  to  speak  not  in  mere  inarticulate 
gibberish,  but  in  distinct  though  irrelevant  words.!  Here, 
however,  it  is  said  that  after  the  fit  by  which  the  lady's  ill- 
ness was  initiated,  "  her  naturally  cheerful  expression  was 
exchanged  for  a  dull  stolid  look,  and  she  took  no  notice 
of  anything."  There  was  evidently  a  condition  of  par- 
tial dementia ;  but  in  a  case  very  briefly  recorded  by 
Trousseau,  in  which  there  was  a  similar  irrelevant  use 
of  words  whose  meaning  was  not  realized  by  the 
speaker,  the  patient  is  said  to  have  been  in  other  respects 

*  As  the  right  Hemisphere  was  open  for  the  reception  of  auditory 
impressions,  it  seems  strange  that  Speech  should  not  have  been 
comprehended  better  in  this  case.  Correct  and  incorrect  auditory 
impressions,  simultaneously  impinging  on  the  two  sides  of  the 
Brain,  might,  however,  produce  so  much  mental  confusion  as  to 
prevent  the  correct  impression  being  renlised. 

t  A  similar  inability  to  understand  what  was  said  by  himseli 
occurred  in  a  patient,  whose  case  is  referred  to  by  Winslow  ("  Ob- 
Bcure  Diseases  of  the  Brain,"  3rd,  Ed.,  p.  328). 


034  THE    CEREBRAL    RELATIONS    OP 

rational  in  her  actions.  She  rose  with  an  air  of  kindness 
to  receive  a  visitor,  and  pointing  to  an  arm-chair,  said, 
**  Cochon,  animal,  fichue  bete!"  whilst  her  son-in-law, 
who  was  present,  and  knew  what  she  really  meant,  said, 
*  Madame  vous  invite  a  vous  asseoir  " — the  lady  all  the 
time  seeming  quite  unconscious  of  the  insulting  expres- 
sions she  had  used. 


b.   Incoordinate  Amnesia. 

The  cases  detailed  in  the  foregoing  section  are  so  dis- 
tinctly illustrative  of  the  *  incoordinate'  defects  of  Verbal 
Memory,  that  we  are  now  naturally  led  on  to  a  considera- 
tion of  the  mode  in  which  these  defects  are  to  be  explained. 
Such  a  wrong  use  of  Words  as  was  encountered  in  the 
case  recorded  by  Dr.  Banks,  is  to  be  met  with  in  very 
various  degrees,  and  constitutes,  in  fact,  one  of  the  most 
common  defects  of  Speech  from  cerebral  disease,  some- 
times showing  itself  more  especially  in  Articulate  Speech, 
sometimes  more  in  Writing — or,  in  other  cases,  the  power 
of  Expression  may  be  nearly  equally  bad  in  both. 

Patients  are  mostly  aware  when  they  make  use  of  wrong 
words  in  either  of  those  modes  of  expressing  themselves, 
though  this  is  by  no  means  always  the  case. 

Luys*  alludes  to  an  instance  where  the  person  was  continually 
in  the  habit  of  using  one  word  for  another  without  being  con- 
scious of  his  mistakes.  One  day  he  pronounced  the  word 
*  jardin,'  wishing  to  say  '  lit,'  repeated  it  several  times,  and  after- 
wards fell  into  a  violent  passion  because  his  orders  were  not  com- 
prehended. He  was  then  made  to  write  the  word  he  wished  to  make 
use  of,  and  the  sir/Jtt  of  the  proper  written  symbols  soon  convinced 
him  that  the  word  which  he  had  actually  uttered  was  not  the  one 
he  had  intended  to  utter. 

•  "  Syst.  Nervcux,"  18G5,  p.  395. 


CiiAP.  XXIX.]  SPEECH    AND    THOUGHT.  635 

Elsewhere*  the  writer  has  given  a  very  good  specimen 
of  a  letter  written  by  a  well-educated  Amnesic  patient, 
fall  of  mistakes,  and  in  some  places  even  unintelligible, 
yet,  judging  from  the  lack  of  erasures,  these  mistakes 
were  apparently  not  observed  by  the  patient  himself. 

The  range  of  these  incoordinate  defects  of  Verbal 
Memory  is  very  various,  both  as  to  frequency  of  occur- 
rence and  as  to  extent.  It  may  be  that  a  wrong  word  is 
only  occasionally  used  in  Speech  or  Writing,  or  such  errors 
may  be  much  more  frequent  and  more  extensive.  It  may 
be  so  extensive  as  to  make  the  person's  Speech  or  Writing 
wholly  irrelevant,  and  even  quite  incomprehensible — owing 
to  the  utterly  confused  collocation  of  actual  words. 

Winslow  has  recorded  an  instance  of  this  extreme 
form  of  amnesic  Speech,  occurring  in  a  gentleman  who 
had  partially  recovered  from  an  apoplectic  attack. 

"  He  could  speak,  but  what  he  said,  without  a  key  to  its  inter- 
pretation, was  quite  unintelligible.  He  was  able  to  pronounce  words 
with  great  clearness,  but  they  were  sadly  misplaced  and  transposed. 
What  he  said  was  written  down,  and  the  words  placed  in  their  proper 
order.  By  adopting  this  course  his  family  were  able  clearly  to 
comprehend  his  wishes.  This  state  of  brain,  and  impairment  of 
speech,  continued,  with  slight  intermissions,  for  nearly  a  fort- 
night." 

The  letters  written  by  Dr.  Banks's  patient  afford  an 
example  of  a  similarly  extreme  defect  in  intellectual 
expression  by  Writing.  Though  made  up  of  properly 
written  words,  the  mode  of  collocation  of  the  latter  was 
such  as  to  convey  no  intelligible  propositions. 

The  explanation  of  the  'paralytic'  defects  of  Yerbal 
Memory  is  a  problem  presenting  no  particular  difficulties  ; 
but  the  same  cannot  be  said  in  regard  to  these  '  inco- 
ordinate '  affections.     There  is  an  obvious  reason,   how- 

*  *•  Paralysis  from  Brain  Disease,"  1875,  p.  189, 


636  THE    CEREBRAL    RELATIONS    OF 

ever,  why  both  the  kinds  of  Speech-defect  should  be  most 
frequently  met  with  in  regard  to  Names  of  persons,  places, 
and  things.  In  the  slighter  cases,  it  is  only  these 
altogether  special  '  associations '  which  either  cannot  be 
recalled  at  all,  or  which  are  misapplied.  It  is  rarer  to 
find  such  defects  extending  to  substantives  generally  and 
to  other  parts  of  speech.  As  Broadbent  truly  observes* 
*'  Words  other  than  names,  such  as  adjectives,  verbs,  etc., 
constituting  the  framework  of  a  sentence  or  proposition, 
stand  on  a  different  footing ;  they  are  not  associated 
with  and  tied  down  by  visual,  tactual,  and  other  percep- 
tions. Their  use  implies  a  previous  knowledge  of  words 
as  names,  and  mark  a  step  beyond  the  act  of  naming. 
They  are  not  substantive  intellectual  sym- 
bols, but  intellectual  agents,  instruments  and  products 
of  intellect  in  action,  not  presentations  impressed  upon  it. 
It  is  with  respect  to  this  class  of  words  that  it  may  be 
strictly  said  that  '  we  think  in  words,'  for  we  often 
think  [in  part]  in  revived  visual  impressions  not  reduced 
to  words.  The  convolutions  concerned  in  their  employ- 
ment, will  be  such  as  are  the  seat  of  the  intellectual 
operations,  the  superadded  convolutions." 

Even  though  we  do  not  quite  agree  with  Broadbent,  in 
supposing  that  Intellectual  Action  and  its  Centres  can  be 
so  distinctly  separated  from  Perceptive  Action  and  its 
Centres  ;  f   or,  in  regard  to  the  divisions  which  he  seeks  to 

♦  "Med.  Chirurg.  Trans.,"  1872,  p.  192. 

f  H.  Spencer  says  ("Principles  of  Psychology,"  vol,  i.  p.  163), 
"The  proximate  components  of  Mind  are  of  two  broadly  contrasted 
kinds — Feelings  and  the  Eelatlons  between  Feelings.''  But  a  close 
examination  of  what  is  said  in  regard  to  '  Relations '  makes  it  evident 
that  they  correspond  with  what  has  been  s))olven  of  generally  in  this 
work  as  the  'cognitive  side  of  Feeling.'  Though  H.  Spencer  names 
two  components  of  Mind  and  describes  them  apart,  this  is  only  for 
descriptive  purposes,  since  he  himself  adds: — "Strictly  speaking 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  637 

establish  between  these  modes  of  activity ;  or  with  his 
explanation  of  the  process  of  Naming — still  what  he 
says  above  is  very  suggestive  in  regard  to  possible  difter- 
ences  of  seat  in  the  organic  substrata  for  Words  accord- 
ing as  they  do  or  do  not  denote  external  objects.*  It  is 
reasonable  to  suppose  that  the  latter  might  be  in  more 
immediate  relation  with  Perceptive  Centres,  whilst  those 
of  ether  parts  of  Speech  would  be  much  more  intimately 
associated  with  regions  where  Perceptive  Processes  become 
merged  into  more  complex  and  more  purely  Intellectual 
Operations. 

Roughly  speaking,  therefore,  the  inability  to  recall 
names,  or  the  miscalling  of  persons,  places,  or  things, 
w^ould  be  defects  going  with  injuries  to  or  altered  states  of 
Perceptive  Centres,  and  might  exist  with  comparatively 
slight  impairment  of  Intellectual  Activity ;  whilst,  on  the 
other  hand,  the  extreme  fcrms  of  Amnesia,  in  which  wholly 
irrelevant  propositions,  or  a  mere  jumble  of  words  are 
uttered,  are  more  likely  to  be  associated  with  marked  im- 

neither  a  Feeling  nor  a  Relation  is  an  independent  element  ol  Con- 
sciousness '" — which  is  exactly  what  Aristotle  and  many  succeeding 
philosophers  have  said,  in  effect  if  not  in  actual  words,  in  regard  to 
Feeling  and  Cognition  (see  p.  182).  The  discrimination  of  a  Feeling 
as  such  and  such  necessarily  comprehends  its  '  relations  '  of  degree, 
kind,  place,  and  time.  And  as  H.  Spencer  says  (loc.  cit.  p.  187): 
— "  Mental  actions,  ordinarily  so  called,  are  nearly  all  carried 
on  in  terms  of  those  tactual,  auditory,  and  visual  feelings,  which 
exhibit  cohesion  and  consequent  ability  to  integrate  in  so  con- 
spicuous a  manner.  Our  intellectual  operations  are  indeed  mostly 
confined  to  the  auditory  feelings  (as  integrated  into  words),  and  the 
visual  feelings  (as  integrated  into  impressions  and  ideas  of  objects, 
their  relations,  and  their  motions)." 

*  Loc.  cit.,  p.  181.  See  also  Dr.  Bristowe's  Lectures  "  On  the 
Pathological  Relations  of  Voice  and  Speech"  ("  Brit.  Med.  Jour- 
nal," May  10, 1879,  p.  691),  for  a  succinct  statement  of  Broadbent's 
view. 

28 


638  THE    CEREBRAL    RELATIONS    OF 

pairment  of  Intellectual  Power — to  be  dependent,  in  short, 
upon  injuries  or  altered  states  of  parts  of  the  Brain  more 
specially  concerned  with  such  modes  of  activity. 

The  process  of  Thought  seems  to  be  in  a  measure 
independent  of  the  Words  in  which  the  Thought  is 
expressed,  so  that  perhaps  we  '  think  in  words  '  somewhat 
less  than  is  generally  supposed.  Its  partial  independence 
appears  indicated  by  the  fact  that  we  'select'  our  expres- 
sions. Thus,  according  to  the  different  shades  of  meaning 
sought  to  be  conveyed  in  our  propositions,  we  often 
deliberately  weigh  or  *  select,'  the  substantives,  adjectives, 
and  verbs,  that  we  may  deem  most  expedient  for  the 
complete  communication  of  our  thoughts  to  others.  This 
seems  to  indicate  some  separate  process  by  which  Thoughts 
or  '  Eelations '  associate  themselves  with  Words — one 
which  is  perhaps  a  little  less  automatic  than  that  by 
which  external  objects,  real  or  in  '  idea,'  associate  them- 
selves with  Words. 

In  the  *  incoordinate  defects'  of  different  grades,  it  is  these 
particular  verbal  relations  or  associations,  which  are  dis- 
turbed. How,  we  know  not.  The  error  may  be  in  the  mode 
of  activity  of  the  Perceptive  or  Thought-Centres,  or  perhaps 
in  their  related  Word- Centres  ;  the  effect,  in  either  case, 
being  that  erroneous  associations  become  established,  so 
that,  as  a  consequence,  incorrect  or  meaningless  proposi- 
tions are  uttered. 

In  the  very  extreme  forms  of  this  incoordinate  defect, 
in  which  Speech  is  reduced  to  a  mere  jabber  of  meaning- 
less sounds,  we  probably  have  to  do  with  some  grave 
defect,  either  in  the  Auditory  Word-Centres  or  in  the 
Kinsesthetic  Word-Centres.  There  are  two  types  of  such 
cases ;  one  like  that  recorded  by  Broadbent,  in  which  the 
person  who  jabbers,  also  docs  not  understand  what  is 
said    to   him ;  and    another  like    that   of  Dr.    Osborne, 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  639 

about  to  be  related,  in  which,  whilst  only  able  himself 
to  talk  gibberish,  the  affected  person  clearly  understands 
everything  that  is  said  to  him.  These  two  types  are 
perhaps  best  explicable  by  defects  in  the  respective  regions 
above  indicated. 

Similarly  extreme  defects  exist  in  regard  to  Writing, 
and  they  may  perhaps  be  similarly  explained  by  some 
defect  in  the  Yisual  Word- Centre,  in  cases  where  the 
power  of  Writing  is  reduced  to  a  mere  meaningless  as- 
semblage of  letters  with  inability  to  comprehend  written 
or  printed  words  ;  whilst,  where  this  latter  disability  does 
not  exist,  the  incoordinate  Writing  may  be  a  mere  defect 
in  execution,  due  to  some  derangement  of  the  Kinsesthetic 
Word- Centre — and  this  seems  a  possible  explanation,  in 
part,  of  the  case  of  the  sailor  recorded  at  p.  6G0. 

Defects  of  this  type,  so  slight  as  to  belong  to  quite  the 
other  end  of  the  scale,  also  exist,  in  which  strange  mis- 
tikes  may,  habitually  or  not,  be  made  in  the  articulation 
of  some  words,  or  in  the  mode  of  writing  them.  Dr. 
Win  slow  mentioned  the  case  of  a  man  w^ho,  after  an  attack 
of  paralys'^s,  always  transposed  the  letters  of  words  in  his 
mode  of  pronouncing  them  ;  thus,  "  endeavouring  to  say 
the  word  '  flute  '  he  said  tufle,  puc  for  '  cup,'  gum  instead 
of  '  mug.'  "  Again,  there  may  be  an  almost  invariable 
substitution  of  certain  letters  for  others — such  as  a  ^  for 
an  /  in  every  word  which  should  have  contained  the  latter 
letter. 

Defects  in  pronunciation  and  defects  of  spelling  of  this 
kind  are  extremely  common  with  patients  who  are  slightly 
Amnesic,  and  to  a  very  slight  extent  may  indeed  be  met 
with  occasionally  in  persons  who  are  otherwise  thoroughly 
healthy.  Such  persons  when  meaning  to  use  one  word 
actually  employ  another — being  sometimes  conscious  of 
their  error  and  sometimes  not ;   and  the  same  holds  good 


610        THE  CEREBRAL  RELATIONS  OF 

for  their  mistakes  in  writing — these  may  he  detected  at 
once,  or  not  till  the  occasion  of  some  suhsequent  perusal 
of  such  writing.  Persons  who  are  liable  to  make  such 
mistakes  in  expression,  may  occasionally  altogether  wrongly 
apprehend  some  word  which  they  hear  spoken  or  which 
they  see  in  writing  or  in  print,  in  a  way  quite  surprising 
to  themselves,  when  the  mistake  is  recognized. 

■  4. — Damage  to  Commissures  hetiueen  the  Auditory  and 
the  Visual  Word- Centres. 

On  reflection  it  will  seem  clear  that  there  must  be  at 
least  two  sets  of  commissures  between  the  Auditory  and 
the  Visual  Word-Centres ;  the  one  (a)  for  transmitting 
stimuli  from  the  Visual  to  the  Auditory  Centres  {visuo- 
auditory  fibres),  as  in  the  act  of  reading  aloud,  or  naming 
at  sight ;  the  other  (b)  for  conveying  impressions  in  the 
opposite  direction,  i.e.,  from  the  Auditory  to  the  Visual 
Centre  {audito-visual  fibres),  as  in  the  act  of  writing  from 
dictation. 

Both  sets  of  commissures  may  be  simultaneously 
damaged,  and  this  seems  to  have  been  the  cause  of  the 
most  notable  defects  met  with  in  two  of  the  writer's  own 
patients,  whose  cases  are  subjoined.  The  first  of  them 
came  under  observation  at  the  National  Hospital  for  the 
Paralysed  and  Epileptic,  in  1869,*  but  nothing  similar  was 
encountered  until  last  summer,  when  the  second  exami)le 
was  seen.  The  writer  is  not  aware  that  any  other  such 
cases  are  on  record. 

A  middle-aged  woman  had  an  attack  of  right  Hemiplegia  wiih 
pretty  complete  Aphasia  in  the  early  part  of  the  year  1868.  In  the 
course  of  some  months  she  improved  considerably,  though  she  con- 
tinued subject  to  'fits'  at  intervals.  After  twelve  months  she  wns 
able  to  walk  about  with  a  little  assistance,  though  she  was  still 

♦  "  Paralysis  from  Brain  Disease,  1875,"  p.  201. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  641 

incapable  of  using  the  right  hand  and  arm.  She  seemed  thoroughly 
to  understand  everything  that  was  said  to  her,  and  had  in  great 
measure  regained  her  power  of  speaking.  She  could  repeat  almost 
any  word  uttered  in  her  hearing,  and  this  without  hesitation, 
though  she  could  not  read  even  the  simplest  words  in  large  type. 
Yet  the  same  words  could  be  uttered  with  ease  immediately  on 
hearing  them  pronounced.  She  copied  the  written  word  '  Lon- 
don '  fairly  tuell  with  her  left  hand,  hut  could  not  write  '  cat '  or 
*  fZo//,'  after  merely  hearing  them  pronounced,  though  she  could 
spell  the  same  words  quite  well.     She  could  not  even  write  the 

first  letter  of  either  of  these   words Twelve   months 

afterwards  she  was  found  to  be  in  much  the  same  condition. 
Could  not  read  aloud  even  such  simple  words  as  *  and  '  and  '  for' ; 
could  point  out  any  letters  which  were  named  with  the  greatest 
ease,  hut  could  not  herself  name  the  letters  when  they  were  pointed 
to.  She  had  improved  in  her  power  of  walking,  and  was  also 
able  to  talk  rather  better.  She  could  read  a  letter  silently  so  as 
to  understand  it,  though  she  did  not  always  seem  to  comprehend 
what  she  read  in  a  newspaper  or  a  book.  When  seen  again,  four 
years  afterwards,  this  patient  was  found  to  be  in  much  the  same 
condition. 

It  is  worthy  of  note  that  during  the  early  stages  of  this 
woman's  illness,  she  seemed  to  be  suffering  from  ordinary 
Aphasia  witli  right-sided  paralysis  ;  it  was  only  after  she 
recovered  her  power  of  Speaking  that  it  was  possible  to 
obtain  evidence  of  the  more  special  defects  above  illus- 
ti^ated,  which  pointed,  as  may  be  seen,  to  a  severance  of 
functional  relation  between  the  left  Auditory  and  Visual 
Word- Centres.  Thus  she  could  not  read  aloud,  neither 
could  she  write  from  dictation — both  of  them  being  acts 
which  require  the  conjoint  activity  of  these  two  Centres.* 
But  she  could  freely  articulate  words  which  she  heard, 
and  could  copy  writing  easily  with  her  left  hand — 
Ijecause  these  were  acts,  one  of  which  called  the  Auditory 

*  Especially  in  persons  not  very  well  educated,  and  therefore  not 
thoroughly  habituated  to  the  performance  of  these  processes.  Ex- 
ceptions, however,  may  occur  to  this  rule  (see  p.  624). 


642  THE    CEREBRAL    RELATIONS    OP 

and  the  other  the  Visual  Centre  into  operation  inde- 
pendently of  the  other.  Tlie  act  of  copying  was  in  this 
case  performed,  as  a  result  of  recent  practice,  with,  the 
left  hand  ;  so  that  the  stimuli  operating  upon  the  motor 
centres  (in  the  right  corpus  striatum)  must  have  imme- 
diately emanated  from  the  Visual  Centre  of  the  right  side, 
T-he  details  of  the  second  case,  which  is  even  moro 
interesting,  are  fuller. 

Thos.  A ,  a  tinplate  worker,  forty-two  years  of  age,  was 

admitted  into  University  College  Hospital,  March  12, 1878.  Three 
months  previously  he  had  become  suddenly  paralyzed  in  the  right 
side  of  the  body,  without  convulsion  or  loss  of  consciousness; 
but  after  the  attack  his  speech  was  found  to  be  almost  lost.  When 
admitted,  he  had  become  able  to  move  his  right  leg  and  arm  slightly  ; 
though  there  was  still  some  diminution  of  sensibility  on  this  side 
of  the  body.  There  was  a  slight  amount  of  right  facial  paralysis, 
and  some  deviation  of  the  tongue  to  the  right.  Sight  and  hearhiq 
were  good.  He  continued  to  improve  slowly,  and  on  April  2  his 
condition  is  thus  described : — He  recognizes  common  objects,  but 
cannot  name  them,  repudiates  a  false  name,  and  recognizes 
the  real  one  at  once  when  he  hears  it.  Can  never  remember  his 
own  name  till  it  is  suggested  to  him.  On  being  asked  to  repeat  it 
(Andrews),  after  a  few  trials  which  vary  each  time  he  pronounces 
it '  Anstruthers '  or  '  Anstrews.'  His  first  name  (Thomas)  seems  to 
come  more  readily,  and  he  can  often  attempt  this  without 
prompting.  But  either  after  it  has  been  repeated  to  him,  or  when 
he  says  it  spontaneously  he  pronounces  it  '  Towvers.'  The  letter  *  L  ' 
is  difficult  for  him  to  utter,  sometimes  he  pronounces  it  like  a  '  D,* 
and  at  others  like  a  'V.'  He  has  been  taught  to  count,  and  can 
fairly  pronounce  the  numerals  from  one  to  tivelve ;  alter  twelve  he 
is  uncertain,  the  articulation  and  order  becoming  rapidly  worse.  He 
is  conscious  when  he  makes  a  mistake,  but  cannot  correct  himself, 
and  ends  in  a  hopeless  muddle.  In  reading  from  a  hooh  the  words 
h,e  ^pronounces  have  no  relation  to  the  print,  either  in  length  or 
sound — neither  does  he  seem  to  tmderstand  written  characters,  as  he 
will  not  attempt  to  answer  a  question  written  on  a  slate,  though  he 
will  at  once  endeavour  to  respond  %vhcn  the  same  question  is  put  to 
him  orally.  He,  however,  recognizes  numerals  from  one  to  nine 
when  written,  and  is  conscious  when  they  are  not  placed  in  regular 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  643 

ort^er.  He  cannot  name  any  coins,  but  seems  to  have  some  idea  of 
their  relative  value.  He  indicated  on  his  fingers  that  sixpence  was 
worth  six  pennies — not  being  able  from  sight  to  utter  its  name. 

On  April  16,  the  patient  had  two  slight  fits,  which,  judging  from 
the  symptoms,  were  apparently  due  to  some  further  slight  damage 
to  the  left  side  of  the  brain.  After  neither  of  these  fits  did  his 
speech  seem  to  be  worse.  The  second,  however,  was  followed  by  an 
aggravation  of  the  right-sided  paralysis,  though  there  was  no  further 
impairment  of  sensibility.  Three  days  afterwards  this  increase  of 
paralysis  had  passed  off,  and  the  patient  was  again  able  to  walk 
about  the  ward. 

Two  weeks  afterwards,  it  was  noted  that  his  speech  was  as  bad  as 
ever;  he  could  name  any  numeral  written  down  and  'pointed  out  to 
him,  and  he  could  also  correctly  add  small  columns  of  three  or  four 
figures;  but  he  altogether  failed  to  name  individual  letters  of  the 
alpliahet,  however  plain  or  large  they  might  be.  He  could  recognize 
common  objects,  such  as  a  dog,  a  fowl,  or  a  tree,  in  an  engraving, 
and  point  out  any  one  of  them  when  asked  to  do  so.  But  he  could 
not  volunteer  the  name  even  of  the  most  familiar  object  to  which 
he  pointed. 

May  8. — Asked  successively  to  name  large,  separate,  printed 
capitals  0,  K,  and  G  from  sight,  on  each  occasion  he  said  '  P,'  and 
on  D  being  pointed  to,  he  called  it  '  M ' — though  he  repeated  the 
name  of  each  of  these  letters  without  a  moment's  hesitation  after 
hearing  it  pronounced.  Although  there  is  this  inability  to  name  let- 
ters from  sight,  thepatient  now  seemsto  understand  simple  sentences 
written  or  printed ;  thus,  when  the  sentence  "  Have  you  a  wife  ?  " 
was  written  on  a  slate,  it  seemed  perfectly  evident  that  he  under- 
stood the  writing.  His  condition,  however,  in  this  respect  seems  to 
vary  from  time  to  time.  In  the  sentences,  the  meaning  of  lahich  he 
comprehends,  he  is  still  quite  unable  to  pronounce  the  individual 
toords  from  sight,  though  after  hearing  them  uttered  he  can  articulate 
tlieyn  at  once,  more  or  less  distinctly. 

Two  days  after,  he  was  observed  reading  something  in  the  news- 
paper, and  on  being  asked  if  he  understood  it  (the  report  of  a  case 
of  poisoning  in  a  police-court),  he  at  once  said  he  did,  and  unmis- 
takeably  indicated  by  his  gestures  that  this  was  true.  Witli  his 
left  hand  he  could  write  his  own  name  after  a  copy,  hut  not 
easily  without,  and  sometimes  not  at  all  A  less  familiar  word 
he  did  not  even  attempt  to  write  from  the  sound,  even  when  it 
had  been  distinctly  heard  and  comprehended. 


644  THE    CEREBRAL    RELATIONS    OP 

It  will  be  observed  that  this  patient's  state  on  A.pril  2 
was  distinctly  different  from  what  it  became  towards  the 
end  of  the  month,  after  the  two  fits.  At  first  he  had  no 
power  of  recalling  the  names  of  common  objects — he 
could  not  name  them  at  sight.  Neither  could  he  volun- 
tarily recall  his  own  name.  And  when,  after  prompt- 
ing, he  endeavoured  to  repeat  words,  his  pronunciation 
showed  distinct  defects  of  the  incoordinate  type.  In 
attempting  to  read  aloud  from  a  book  these  incoordinate 
defects  were  so  marked,  as  to  make  what  he  read  quite 
unintelligible ;  neither  did  he  seem  to  comprehend  any 
written  characters  except  simple  numerals.  Towards 
the  end  of  April,  however,  whilst  the  patient's  utterance 
had  become  more  distinct  in  repeating  words  which  he 
had  heard,  he  could  not  even  emit  an  unintelligible  jargon 
in  attempting  to  read.  At  the  same  time  he  had  become 
able  to  understand  what  he  read,  though  he  still  could  not 
name  even  a  single  letter  at  sight,  nor  could  he  write  a 
single  word  from  dictation — both  these  latter  processes 
requiring  for  their  performance  the  proper  relation 
(and  therefore  the  integrity  of  the  commissures)  between 
the  Visual  and  the  Auditory  Word- Centres.  That  part  ol 
the  commissure  which  conveys  stimuli  from  the  Visual  to 
the  Auditory  Word-centres  (as  in  reading  aloud)  seems  to 
have  been  more  extensively  damaged  after  the  two  fits 
than  it  was  before.  The  fact,  however,  that  he  could  read 
and  pronounce  the  names  of  numerals  suggests  the  possi« 
bility  that  these  more  familiar  units  may  have  been 
articulated  by  means  of  stimuli  passing  direct  from  the 
Visual  Word- Centre  to  the  half  of  the  Kinaesthetic  Word- 
Centre  concerned  with  Speech-Movements  (see  p.  624). 

Dr.  Broadbent  has  recorded  an  extremely  rare  and 
interesting  result  of  cerebral  disease,  closely  allied  to  that 
found  in  the  two  cases  just  related.     His  patient,  however, 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  645 

had  not  lost  the  power  of  'voluntary'  or  of  'associational' 
recall  in  the  Auditory  Word- Centre.  He  spoke,  in  fact, 
fluently,  and  with  only  an  occasional  hesitation  ;  though 
he  was  unable  to  write  at  will. 

The  patient,  a  gas-inspector  of  remarkable  energy  and  intelli- 
gence, after  an  acute  cerebral  attack  had  entirely  lost  the  power  of 
naming  objects  at  sight  and  of  reading.  He  talked  fluently  and 
intelligently,  scarcely  ever  made  a  mistake  in  words,  but  was  some- 
times at  a  loss  for  a  name,  especially  of  a  street,  place,  or  person. 
He  was,  however,  quite  unable  to  read,  or  even  to  name  a  single 
letter;  the  only  exception  being  that  he  recognized  his  own  name, 
whether  written  or  printed ;  though  even  here  he  did  not  know 
whether  the  Christian  names  or  initials  only  were  given.  Whilst 
this  was  the  case,  he  wrote  correctly  from  dictation,  and  took  notes 
of  my  instructions^  which  he  could  not  read  a  moment  afterivards.* 
He  explained  that  he  was  forgetful,  and  his  wife  would  make 
them  out.  If  a  hand,  or  an  article  of  clothing,  or  any  familiar 
object  were  shown  him,  he  was  quite  unable  to  name  it ;  while  if 
the  name  came  up  in  conversation  he  spoke  it  without  hesitation. 
Asked  the  colour  of  a  card,  he  could  not  give  it.  "  Is  it  blue.P  " 
**No."  "  Green  P"  "No."  "Bed?"  "Well,  that's  more  like 
it."  "  Orange  ?  "  "  Yes,  orange."  A  square  and  a  circle  were 
drawn,  and  he  was  asked  to  name  either.  He  could  not  do  it ;  but, 
when  the  circle  was  called  a  square,  he  said,  "No,  but  that  is," 
pointing  to  the  proper  figure. 

The  injury  of  a  single  set  of  commissural  fibres  (the 
visuo-auditory),  with  the  addition  of  some  slight  defect 
in  the  Visual  Word-Centre,  would  produce  such  a 
combination  3f   symptoms  as   are   above  recorded.     We 

*  In  the  more  detailed  account  of  this  case  it  is  said  he  could 
not  read  his  own  writing  "  an  hour  later."  It  seems  that  there  was 
more  than  an  inability  to  read  aloud.  He  showed  an  inability  to 
comprehend  words  (from  defect  in  the  Visual  Word-Centre),  such 
as  did  not  exist  in  the  previous  cases,  though  there  was  no 
inability  to  recognize  the  nature  of  common  objects  or  even  of 
geometrical  figures. — "  Brit.  Med.  Jrnl.",  April  8,  1876,  p.  434,  or 
with  more  detads  in  "  Med.  Chir.  Trans.,"  1872  (Case  viii.). 


G46        THE  CEREBRAL  RELATIONS  OP 

have  supposed  that  impressions  made  on  the  Visual 
Centre  usually  pass  from  it  to  the  Auditory  Word- Centre, 
and  thence  through  the  Kinsesthetic  to  the  Motor  Centres  if 
the  Sight-impressions  are  to  be  named  articulately.  But  if 
merely  this  set  of  commissural  fibres  were  damaged,  the 
individual  would  be  left  with  his  Sight  intact,  and  with 
his  ordinary  powers  of  Speech  intact — he  would  simply  be 
unable  to  read  or  to  name  from  sight,  because  of  the  block 
between  the  Visual  and  the  Auditory  Centres.  In  this 
particular  case,  however,  the  block  seems  to  have  been 
only  partial;  since  the  man  could  still  write  from  dictation 
— a  process  usually  necessitating  the  passage  of  stimuli 
from  the  Auditory  to  the  Visual  Word-Centres,  before  the 
excitation  of  those  parts  of  the  Kina^sthetic  Word-Centres 
concerned  with  Writing-movements  and  whence  issue  the 
appropriate  outgoing  stimuli. 

Still  it  is  possible  that  both  the  sets  of  commissural 
fibres  may  have  been  destroyed,  and  that  in  this  case  of  a 
better  educated  man,  his  more  familiar  Writing-movements 
may  have  been  evoked  by  the  passage  of  stimuli  direct  from 
the  Auditory  to  the  Kinsesthetic  Word- Centre — rather  than 
by  way  of  the  Visual  Centre  (see  p.  644). 

Dr.  Broadbent  interprets  this  case  quite  differently.  His 
opinion,  however,  as  to  the  separate  existence  of  a  single 
'  naming  centre '  altogether  apart  from  the  Perceptive 
Centres,  is  not  here  adopted.  We  have  postulated  in- 
stead the  existence  of  three  *  word-centres '  as  important; 
and  intimately  correlated  parts  of  the  more  general  Audi- 
tory, Visual,  and  Kinassthetic  Centres.* 

*  It  is  difficult  to  get  evidence  of  the  existence  and  special 
activity  of  the  liist-named  component  of  this  triad,  but  since  the 
above  was  written  the  author  has  seen  in  Von  Zienissen's  "  Cyclo- 
l)a3dia,'*  vol.  xiv.  p.  776,  a  short  abstract  of  an  exceedingly  interesting 
case  (recorded  by  Westphal)  having  some  relations  with  that  abovo 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  647 

The  three  principal  cases  recorded  in  this  section  are 
particularly  important  from  a  psychological  point  of  view. 
They  enable  us  to  trace  Will  or  Volition  to  its  sources 
— when  we  find  persons  unable  to  Will  an  act  in  response 
to  a  Visual  Impression,  though  they  can  at  once  and 
without  hesitation  effectively  Will  the  same  act  in  response 
to  a  related  Auditory  Impression — or  vice  versa  (pp.  353, 
855). 

B.  Aphasia. 

5. — Damage  to  the  first  parts  of  the  outgoing  tracks 
leading  from  the  Cerebral  Word- Centres  to  the  left  Corpus 
Striatum, 

Hitherto  we  have  been  considering  defects  resulting 
from  abnormal  conditions  of  the  Auditory  and  Visual 
Word- Centres    themselves,    or    from     injuries    to    their 

*  afferent '  or  *  commissural '  fibres ;  now  we  turn  to  the 
illustration  of  the  results  following  upon  injuries  to  the 

*  outgoing '  fibres  from  these  and  from  the  Kinsesthetic 
Word-Centres — those  which  bring  them  into  relation  with 

given,  and  affording  also  some  information  of  the  kind  referred 
to.  Of  this  patient  it  is  said: — "He  could  write  very  well  from 
dictation,  but  shortly  after  he  was  unable  to  read  the  words  he  had 
written,  and  he  suffered  in  general  from  complete  alexia  [i.e. 
inability  to  comprehend  written  symbols].  By  means  of  a 
stratagem,  however,  as  he  himself  very  clearly  explained,  he  suc- 
ceeded in  reading  the  word  he  had  written  from  dictation  upon  the 
tablet.  He  passed  his  finger  over  each  letter  of  the  written  word 
as  if  he  were  writing  it  again  and  read  it  while  so  doing.  He  then 
made  a  sort  of  calculation  and  counted  off  the  sum  of  the  separate 
letters,"  Here  apparently  the  Kinsesthetic  Impressions  from 
Writing-movements  were  capable  of  rousing  related  parts  of  the 
Auditory  Word-Centre  so  as  to  enable  them  to  act  through  the 
other  portion  of  the  Kinsesthetic  Word-Centre,  and  thus  evoke 
Speech-movements. 


648  THE    CEREBRAL    RELATIONS    OF 

the  Motor  Centres,  concerned  with  Speech-movements 
and  with  Writing-movements,  in  the  Corpus  Striatum. 

The  relation  existing  between  the  Auditory  and  Visual 
Word-Centres  and  the  parts  of  the  Kinsesthetic  Word- 
Centres  to  which  impressions  derived  from  Speech-move- 
ments and  Writing- movements  respectively  proceed,  are 
confessedly  uncertain.  There  is  reason  to  believe,  how- 
ever, that  the  incitations  which  evoke  Speech  start 
primarily  from  the  Auditory  Word- Centre,  and  then 
pass  through  the  corresponding  Kin£esthetic  Word-Centre, 
so  as  to  rouse  it  into  conjoint  and  practically  simultaneous 
activity.  Similarly,  there  is  reason  to  believe  that  the 
incitations  which  evoke  Writing-movements  start  primarily 
from  the  Visual  Word- Centres,  and  thence  pass  through 
the  related  parts  of  the  Kinesthetic  Word-Centres. 

It  is  clear,  therefore,  that  destruction  of  the  Auditory 
and  of  the  Visual  Word- Centres  would  cause  inability  to 
Speak  and  inability  to  Write.  These  disabilities  w^ould, 
however,  be  associated  with  such  defects  as  have  been 
considered  under  the  head  of  Amnesia — viz.,  inability  to 
comprehend  Speech  and  Writing,  together  with  inability 
to  revive  Auditory  and  Visual  ideas  of  Words. 

What  w^e  are  specially  concerned  with  in  the  present 
section  are  the  results  that  follow  upon  damage  to  the 
outgoing  fibres  leading  from  the  left  Auditory  and  Visual 
through  the  Kinsesthetic  Word-Centres,  to  the  great  Motor 
Ganglion  beneath — viz.,  the  Corpus  Striatum. 

It  would  seem  that  these  two  sets  of  outgoing  channels 
are,  at  all  events  in  some  parts  of  their  course,  situated 
moderately  close  together,  so  that  they  may  be  destroyed 
simultaneously  by  some  small  lesion,  and  that  too  without 
the  implication  of  outgoing  fibres  for  limb-movements — • 
and  consequently  without  the  association  of  a  right-sided 
paralysis.     One  of  the  two  cases  originally  described  by 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  6i9 

Broca,  in  1861  * — that  of  Lelong — evidently  conformed 
to  this  type,  but  as  he  did  not  come  under  observation 
till  some  time  after  the  commencement  of  his  malady,  we 
select  a  fairly  typical  case  recorded  by  Dr.  Bateman.f 

A  waterman,  fifty-one  years  of  age,  and  previously  healthy, 
after  helping  to  unload  a  vessel  at  Yarmouth  on  December  9,  l864, 
went  to  a  tavern  with  the  intention  of  asking  for  some  beer,  when, 
to  his  astonishment,  he  found  himself  unable  to  speak.  Only  a 
few  hours  previously  he  had  called  at  a  merchant's  office  and 
arranged  about  a  fresh  cargo,  so  that  at  this  time  his  aptitude  for 
business  was  in  no  wise  impaired.  His  loss  of  speech  was  ac- 
companied by  no  ordinary  paralytic  condition,  for  although 
speechless,  he,  on  the  same  evening,  removed  his  vessel  from  one 
part  of  the  river  to  another,  and  the  next  day  he  helped  to  reload  it 
with  a  fresh  cargo  before  starting  for  JSTorwich  by  rail.  On  reach- 
ing home  his  friends  were  alarmed  at  finding  that  his  vocabulary 
was  limited  to  the  words,  "Oh  dear!  Oh  dear!"  There  was  no 
marked  improvement  till  the  expiration  of  a  fortnight :  after  this 
period  he  seems  gradually  to  have  become  able  tp  utter  a  few  more 
words.  When  seen  by  Dr.  Bateman  about  three  months  and  a 
half  from  the  commencement  of  his  illness  he  looked  well,  seemed 
remarkably  intelligent,  and  appeared  to  understand  everything 
that  was  said  to  him.  He  was  still  unable  to  give  expression  to  his 
ideas  by  articulate  language,  except  in  a  very  imperfect  manner, 
though  he  could  move  his  tongue  freely  in  all  directions.  He  had 
been  able  to  write  fluently  before  the  date  of  his  illness,  but  he 
had  almost  lost  this  power,  as  well  as  that  of  speech.  Although 
just  able  to  write  one  or  two  words,  he  could  not  write  a  sentence. 
Yet  there  was  no  trace  of  paralysis  of  limbs,  either  on  the  right  or 
on  the  left  side. 

Later  this  man  became  subject  to  fits  at  short  intervals. 
After  nearly  two  years,  he  was  again  admitted  to  the  Hospital,  on 
January  12,  1867.  He  then  seemed  in  the  possession  of  his  usual 
intelhgence,  and  was  still  free  from  any  signs  of  paralysis  in  limbs 
or  face.  He  had  regained  the  power  of  speaking  to  a  considerable 
extent,  and  now  suffered  from  a  different  kind  of  defect — he  had 
become  Amnesic  rather  than  Aphasic.   "  He  understands  all  thatia 

*  "  Bullet,  de  la  Soc.  Anatom.,"  Aug.  and  Nov.  1861. 
t  "  On  Aphasia,"  1870,  p.  65. 


650        THE  CEREBRAL  RELATIONS  OF 

said,  but  is  affected  with  an  incapacity  to  employ  substantives*, 
having  lost  the  memory  of  words  as  far  as  that  part  of  speech  is 
concerned,  and  he  will  make  use  of  a  periphrasis  to  avoid  using  the 
substantive  required."  A  few  months  afterwards  he  became  para- 
lysed, and  soon  after  that  so  demented  as  to  necessitate  his  remova? 
to  the  Borough  Asylum. 

This,  in  its  first  stage,  seeDis  to  have  been  a  case  of 
Aphasia  pure  and  simple.  Trousseau  records  several 
instances  in  which  such  a  condition  lasted  only  a  few  days 
or  perhaps  only  a  few  hours,  owing  to  the  existence  of 
some  temporary  abnormal  cerebral  condition — induced 
occasionally  without  apparent  cause,  and  at  other  times  as 
a  sequence  of  some  great  excitement  conjoined  with  '  worry* 
or  over-work.  Such  cases  are  not  extremely  rare;  two 
or  three  of  them  have  also  fallen  under  the  notice  of 
the  writer. 

When  however  an  actual  lesion  exists,  of  greater  mag- 
nitude than  that  which  may  have  been  present,  in  the  first 
stage  of  Dr.  Bateman's  case,  it  often  happens  that  the 
Aphasia  co-exists  with  a  paralysis  of  the  right  side  of  the 
body — or  a  right  Hemiplegia,  as  it  is  termed. 

The  larger  the  lesion,  too,  the  greater  is  the  chance 
that  the  Visual  or  the  Auditory  Centres  themselves,  or 
some  of  their  commissures  may  be  seriously  damaged  : 
with  the  effect  of  producing  an  admixture  of  Amnesic 
symptoms  with  those  of  Aphasia.  Such  additional  symp- 
toms may  reveal  themselves  either  from  the  first,  or  only 
as  the  individual  begins  to  recover  from  the  Aphasic 
condition. 

Three  instances  of  complications  of  this  sort  will  now  be 
given.  The  first  of  them  being  a  case  recorded  by 
Trousseau,  in  which  Aphasia  was  produced  by  a  lesion  that, 
at  the  same  time,  caused  right-sided  paralysis  together 
with  inability  to  read — the  latter  disability  being  prob- 
ably due  to  damage  of  the  left  Visual  Word-Centre. 


CuAP.  XXIX.l  SPEl.CH    AND    THOUGHT.  651 

M.  X — ,  get.  57.  One  evening  whilst  rising  from  his  chair  to 
ehake  hands  with  the  curate  of  the  place,  he  suddenly  staggered, 
stammered,  and  dropped  into  the  arms  of  his  visitor,  who  had 
rushed  forward  to  support  him.  He  remained  in  a  most  profound 
apoplectic  stupor  for  more  than  ten  hours  with  complete  paralysis  of 
the  right  side.  For  a  few  days  he  gave  only  obscure  signs  of  intelli- 
gence; but  from  the  time  of  this  seizure  he  entirely  lost  the  faculty 
of  speech.  A  few  months  afterwards  (summer  of  1860),  he  almost 
completely  recovered  the  power  of  moving  his  right  leg,  but  the 
movements  of  his  right  arm  have  always  been  impeded. 

In  the  spring  of  1863,  M.  X —  was  seen  by  Trousseau,  who  gave 
the  following  account  of  him  : — "  His  face  was  intelligent,  cheerful, 
and  full  of  benevolence.  He  seemed  by  his  gestures,  and  especially 
by  the  expression  of  his  face,  pleased  to  see  me.  He  could  not 
speak,  and  only  uttered  in  a  faltering  voice  unintelligible  words,  in 
which  the  monosyllable  '  Yes ! '  returned  frequently.  When  I 
questioned  him  he  answered  '  Yes .'  *  to  everything,  ev.'^n.  when  he 
shook  his  head  in  denial.  '  How  old  are  you  ?  ' — '  Yes  I '  How- 
far  back  do  you  date  your  illness  ?  ' — '  Yes, '  &c.,  &c.  It  could  be 
easily  seen,  however,  that  he  was  not  satisfied  when  the  word  '  Yes' 
was  wrongly  applied,  for  he  then  made  an  impatient  gesture.  He 
looked  pleased,  on  the  contrary,  when  the  word  was  used  appro- 
priately. He  sat  to  table  with  us  at  dinner,  used  his  left  hand, 
and  ate  with  great  propriety.  He  looked  after  his  guests  during 
dinner,  and  took  part  in  some  of  the  discussions  carried  on.  When 
the  delicate  character  of  the  lamb  of  the  country  was  praised,  he 
nodded  assent ;  whilst  on  some  of  the  guests  saying  that  the  kid  of 
the  country  had  a  better  flavour  than  the  lamb,  he  shook  his  head 
in  disapproval.  He  made  signs  to  the  servants  to  hand  the  wine, 
and  when  wine  of  an  esteemed  vintage  was  going  round  he  made 
signs  that  it  should  be  drunk  in  preference  to  the  rest." 

"  He  played  every  day  at  '  all-fours,'  hiding  his  cards  behind  a 
pile  of  books,  and  using  his  left  hand.  He  often  won  when  playing 
with  the  curate,  the  doctor,  or  his  son,  without  their  allowing  him 
to  do  so  out  of  kindness.  His  son  and  Dr.  Lafl&te  declared  to  me 
that  he  played  as  well  as  he  ever  used  to  do.  Sometimes  his  son 
sits  by  his  side  to  advise  him,  and  stops  him  when  he  takes  a  card 
which  seems  not  to  be  the  proper  one,  but  he  insists  on  playing  as 
he  likes,  and  by  winning  the  game  proves  to  his  adviser  that  if  he 
sacrificed  a  card  it  was  because  he  could  thus  improve  his  game. 
Although  his  son  manages  all  his  affairs,  he  insists  on  being  con- 


652  THE    CEREBRAL    RELATIONS    OF 

suited  about  his  leases,  contracts,  &c. ;  and  his  sou  stated  to  me 
that  his  father  indicates  perfectly  well  by  gestures  which  are 
understood  by  those  habitually  around  him,  when  certain  portions 
of  the  deeds  do  not  please  him,  and  that  he  is  not  satisfied  till 
alterations  are  made,  which  are,  as  a  rule,  useful  and  reasonable." 

Although  Ids  sight  was  good  he  could  not  read,  or  at  least  under- 
stand the  sense  of  what  he  read ;  he  listened  with  pleasure,  hoioever^ 
luhen  he  was  read  to.  He  could  not  'put  together  loose  letters  of 
the  alphabet,  nor  write  with  his  left  hand. 

"  After  dinner,"  Trousseau  says,  "  I  tried  to  make  out  how  far  he 
could  give  proof  of  intelligenoe."^  As  he  always  answered  '  Yes,'  I 
asked  him  whether  he  knew  how  that  word  was  spelt,  and  on  his 
nodding  assent  I  took  up  a  large  quarto  volume,  with  the  following 
title  on  its  back  :  '  History  of  the  Two  Americas,'  and  requested  him 
to  point  out  the  letters  in  those  words  which  formed  the  word  '  Yes.' 
Although  the  letters  were  more  than  one-third  of  an  inch  in  size, 
he  could  not  succeed  in  doing  as  I  wished.  By  teUing  him  to  seek 
for  each  letter  in  turn,  and  by  calling  out  its  name,  he  managed 
after  some  hesitation  to  point  out  the  first  two,  and  was  very  long 
in  finding  the  third.  I  then  asked  him  to  point  out  the  same 
letters  again,  without  my  calling  them  out  first,  but  after  looking  at 
the  book  attentively  for  some  time,  he  threw  it  away  with  a  look  of 
annoyance,  which  showed  that  he  felt  his  inability  to  do  as  I 
wished  him." 

It  has  often  happened  to  him  to  say  a  word  which  he  has  not 
uttered  for  a  very  long  time,  as  if  an  old  impression  were  revived 
in  his  brain.  Some  time  ago  he  dropped  his  handkerchief,  and  as 
a  lady  near  him  picked  it  up  and  gave  it  to  him,  he  said  to  her, 
*'  Thanlcs  /  "  in  a  loud  and  distinct  voice.  His  friends  were  de- 
lighted at  this,  and  thought  that  he  had  recovered  his  speech.  He 
was  asked,  implored,  to  say  the  word  again  ;  it  was  repeated  to 
him  several  times,  but  all  was  in  vain,  he  never  could  succeed  :  and 
this  was  the  general  rule,  he  could  not  even  repeat  the  simplest 
sound  wliich  had  hecn  uttered  before  him.  He  told  his  age  correctly 
in  a  most  ren^.arkable  way,  with  his  fingers. 

*  "What  follows,  however,  is  rather  to  be  regarded  as  evidence 
bearing  upon  the  functional  activity  of  his  Visual  Word-Centre, 
which  was  very  defective.  It  constitutes  no  measure  of  the  degree 
of  the  patient's  intelligence,  since  this  (as  shown  by  a  previous 
paragraph)  was  well  preserved. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  653 

In  the  case  next  selected,  the  Aphasia  was  also  asso- 
ciated with  right-sided  paralysis,  but  it  was  accompanied 
by  considerable  mental  impairment,  and  there  was  evi- 
dence of  the  existence  of  damage  not  only  to  the  Visual 
but  also  to  the  Auditory  Word-Centres.  The  patient 
could  neither  Speak  nor  Write.  Moreover,  she  did  not 
seem  to  be  able  to  apprehend  the  meaning  of  spoken 
words,  and  she  was  equally  at  a  loss  to  understand  written 
or  printed  characters.  This  case  was  recorded  by  Dr. 
Bazire.* 

"M.  W — ,  Eet.  24,  a  young  woman  of  short  stature,  was  admitted 
as  an  out-patient  at  the  N'ational  Hospital  for  the  Paralj'sed  and 
Epileptic  on  January  10,  1865,  suffering  from  imperfect  right 
hemiplegia,  and  complete  aphasia.  To  all  my  questions  she  invari- 
ably answered,  '  Sapon,  Sapon.'  It  was  ascertained  from  a  relative 
who  accompanied  the  patient,  that  she  had  been  seized  with  para- 
lysis on  the  right  side  three  months  previously.  The  actual  attack 
was  sudden.  She  dropped  down  senseless,  remained  in  a  comatose 
condition  for  several  days,  and  when  she  recovered  her  senses  could 
not  utter  a  single  word  beyond  '  Sapon,  Sapon,'  which  she  has  ever 
since  kept  repeating  at  every  turn.  The  paralysis  was  not  com- 
plete after  the  first  few  days." 

"  When  I  first  saw  her  the  patient  had  walked  to  the  hospital,  a 
distance  of  about  two  miles  from  her  residence.  Her  face  was  full 
of  expression,  and  her  eyes  beaming  with  intelligence;  yet  it  was 
manifest  that  these  appearances  were  deceptive,  and  that  her 
intellect  was  very  much  impaired.  She  could  not  he  made  to  un- 
derstand at  once,  hij  words  alone,  what  was  required  of  her ;  and 
could  not  always  answer  correctly  hy  gestures  the  questions  which 
she  was  ashed.  Her  'pantomime  was  not  so  clear  as  that  of  a  deaf 
and  dumh  individual,  and  she  seemed  not  to  be  ahle  to  understand 
the  meaning  of  words.  They  had  to  be  sjpohen  very  slowly,  and 
repeated  several  times  before  she  could  catch  their  meaning,  and  she 
•most  frequently  failed  completely  in  this.  Gestures  she  understood 
at  once.  Thus,  when  I  asked  her  to  show  me  her  tongue,  she 
did  not  always  do  so  immediately ;  but  on  putting  out  my  own 

*  Trousseau's  "  Lectures,"  Trans,  p.  224. 


C54  THE   CEREBRAL    RELATIONS    OF 

tongue,  and  then  making  signs  to  her  to  do  the  same,  she  instanihj 
complied.  She  was  prone  to  shed  tears  or  to  laugh  immoderately 
for  the  least  thing,  as  ordinary  hemiplegias  are  well  known  to 
do,  at  a  certain  period  of  their  complaint.  She  could  not  write  a 
single  word  with  her  left  hand  ;  she  held  her  fen  properly,  hit  only 
made  a  meaningless  scraiul.  Although  she  Tcept  constantly  repeating 
*  Sapon,  Sapon,^  I  could  never  mahe  her  say  '  8a,p'  or  'pon'  hy 
itself,  or  repeat  any  syllahle  or  word  after  me.  8he  knew  her  own 
name,  and  when  I  mentioned  it  she  laughed  and  pointed  to  herself. 
According  to  her  sister's  statement  she  remembered  localities  and 
knew  faces  well." 

A  month  after  she  came  under  observation,  she  had  further 
acute  cerebral  symptoms  which  increased  her  paralysis,  and  also 
still  further  clouded  her  intellect  for  a  time.  But  by  slow  degrees, 
and  after  an  interval  of  many  months,  she  improved  remarkably,  so 
that  by  the  following  October  she  was  considerably  better  in  many 
respects.  Dr.  Bazire  continues  : — "  Her  intellect  was  improved,  but 
not  in  the  same  proportion  as  the  paralysis.  Her  emotional 
excitability  is  much  less  than  before,  although  it  is  still  marked. 
Her  vocabulary  comprises  now  a  few  more  words.  She  still  says 
Sapon,  Sapon,  but  she  can  now  distinctly  articulate  yes  and  wo, 
although  she  does  not  always  use  them  appropriately,  and  she  can 
count  one,  tivo,  three,  four.  When  under  the  influence  of  great 
excitement  she  sometimes  exclaims,  '  Oh,  dear  me,'  according  to 
her  sister's  account.  She  cannot  yet  write  a  single  word,  nor  even 
form  a  single  letter,  although  she  has  often  tried  hard.  She  does 
not  know  the  letters  of  the  alvhahet,  and  when  she  is  shown  a  and  o, 
and  asked  to  point  out  a,  she  cannot  do  it.  She  has  still  great 
dijjlculty  in  understanding  what  is  said  to  her  in  words,  although 
she  is  not  in  the  least  hard  of  hearing  ;  hut  she  immediately  under- 
stands gestures.  Her  own  pantomime  still  lacks  clearness.  She 
never  reads,  but  is  fond  of  looking  at  pictures." 

The  next  case  of  Aphasia  to  be  recorded,  was  one 
whicli  came  under  the  care  of  the  writer.  There  was 
here,  also,  the  association  with  right  Hemiplegia,  hut 
both  it  and  the  mental  impairment  were  much  moro 
marked  than  in  the  last  case.  There  was  the  same  loss 
of  ability  to  Read;  and  some  difficulty  in  apprehending 
Speech,  whilst  in  addition   there  was  an  imperfect  power 


Cn^p.  XXIX.]  SPEECH    AND    THOUGHT.  655 

of    comprehending  signs,   and  an   inability  to  Will  and 
execute  even  Mie  simplest  motor  acts. 

M.  C — ,  a3t.  24,  had  suffered  much  mental  distress  owing  to  the 
recent  death  of  one  of  her  children.  On  October  3rd  she  had  a  lit 
for  the  first  time,  whilst  in  the  street,  but  was  able  to  walk  home, 
and  during  the  two  days  which  intervened  before  her  admission 
into  University  College  Hospital  she  had  twelve  other  epileptiform 
attacks. 

Soon  after  her  admission,  kho  had  another  series  of  convulsions, 
affecting  both  sides  of  tho  body,  though  principally  the  right. 
During  the  intervals  between  tiie  separate  attacks,  it  was  found 
that  her  face  was  partially  paralysed  on  the  right  side,  the  right 
arm  was  completely  paralysed,  and  tne  ieg  to  a  less  extent.  She  had 
six  series  of  these  convulsive  attacks  m  the  three  days  following 
her  admission,  and  during  this  time  remained  in  a  dull,  lethargic 
state.  On  October  I3th  she  gradually  began  to  regain  a  certain 
amount  of  intelligence  in  look  and  manner. 

On  the  19th,  her  attention  could  be  an  once  arrested;  she  made 
decided  efforts  to  speak  after  questions,  and  was  able  to  say  'yes* 
and  'no'  indistinctly,  though  not  appropriately.  When  told  to 
show  her  tongue  she  merely  opened  her  mouth,  not  attempting  to 
protrude  the  organ.  Was  able  to  swallow  wiihout  difficulty,  and 
took  food  eagerly.  On  the  26th,  seemed  still  more  intelligent. 
Did  not  protrude  the  tongue  when  told,  but  opened  her  mouth 
and  took  hold  of  the  tip  with  her  fingers,  with  the  view  of  bringing 
it  forwards.  Although  unable  to  move  it  hy  an  unaided  volitional 
stimulus,  on  a  sweet  lozenge  being  applied  to  her  lips  she  imme- 
diately put  out  her  tongue  with  great  readiness,  and  whilst  eating 
it  laughed  and  seemed  much  'pleased.  On  the  28th,  looked  much 
brighter,  and  took  notice  of  what  passed  around  her.  Made  signs 
when  she  wished  to  attract  the  attention  of  the  nurse.  When  asked 
if  she  had  pain  in  the  head,  she  nodded  assent;  but  did  not  move 
her  hand  when  told  to  place  it  upon  the  painful  part,  or  else 
moved  it  in  quite  a  different  direction.  Paralysis  of  limbs  and 
face  continued  much  the  same. 

About  ten  days  afterwards  I  examined  her  again  carefully.  Shehad 
continued  to  improve  in  the  meantime,  and  could  now  say  'Nurse' 
distinctly,  in  addition  to  '  Yes '  and  'No.'  She  could  not  repeat 
the  simplest  vowel  sounds,  neither  could  she  read  single  words  in 
lurge  print,  either  aloud  or  to  herself,  so  as  to  comprehend  them. 


656  THE    CEREBRAL    RELATIONS    OF 

She  could  not,  in  fact,  point  out  individual  capital  letters  of  very 
large  type.  When  asked  to  pclnt  out  M,  after  a  long  time,  and 
much  pressing,  she  placed  her  finger  upon  "W ;  and  when  told  that 
she  was  not  right,  and  asked  to  point  out  W,  after  a  still  longer 
interval,  she  laid  her  finger  upon  S.  She  seemed  to  recognize 
familiar  objects  and  hnow  when  the  right  name  was  given  to  them. 
She  could  not  he  made  to  count  hy  tapping  with  her  forefinger, 
although  she  had  been  shovm  most  carefully  what  she  loas  to  do. 
She  could  not  even  he  induced  to  give  a  single  tap,  and  only  looked 
distressed.  She  seemed  to  recollect  her  own  name.  And  although 
she  did  not  give  any  signs  of  recognition  when  the  name  of  the 
street  in  which  she  lived  was  mentioned,  she  immediately  nodded 
assent  when  she  heard  the  remaining  part  of  her  address— viz., 
•'  Fitzroy-square,"  pronounced.  She  rarely  laughed,  but  frequently 
had  fits  of  crying.  She  uttered  no  additional  exclamations  when 
excited,  and  her  vocabulary  was  confined  to  the  three  words  above 
mentioned. 

This  is  a  food  example  of  one  of  the  severer  forms  of 
disease,  in  which,  beyond  the  Aphasia,  with  defective 
activity  of  the  Auditory,  and  especially  of  the  Visual 
Word-Centres,  there  was  a  general  impairment  of  mental 
power  due,  in  all  probability,  to  the  extensive  nature  of 
the  lesion  in  the  left  Cerebral  Hemisphere. 

As  a  connecting  link  between  the  slighter  cases  pertain- 
ing to  this  category  and  those  of  the  next — Agraphia — - 
a  good  example  may  be  quoted  from  Trousseau.  It  is 
an  instance  in  which  there  was  greater  damage  to  the  out- 
going fibres  from  the  Visual  than  to  those  from  the 
Auditory  Centre — since  when  the  individual  had  regained 
some  of  his  lost  ability  to  Speak,  he  still  continued  unable 
to  express  his  thoughts  by  Writing. 

"A  young  labourer,  a3t.  28,  had,according  to  the  statement  of  his 
friends,  been  seized,  suddenly  and  without  any  assignable  cause, 
with  complete  mutism. 

"  The  affection  for  which  he  came  to  the  Hospital  consisted  solely 


CffAP.  XXIX.]  SPEECH    AND    THOUGHT.  657 

in  an  utter  inahilitij  to  spcah,  althourjli  Ms  intelligence  seetned  to  he 
unimpaired,  and  he  could  perfectly  understand  all  the  questiona 
that  were  put  to  him.  But  to  these  questions  he  invariably- 
answered  *  No,'  even  when  he  nodded  his  head  to  signify  assent. 
One  of  the  students,  however,  informed  me  that  when  left  alone 
with  him,  he  had  succeeded  in  making  him  say  the  word  '  cloah,* 
after  many  repeated  trials.  I  found  only  a  marked  deviation  of 
the  apex  of  the  tongue  to  the  right,  but  no  other  sign  of  paralysis; 
the  face,  the  trunk,  and  limbs,  could  be  moved  with  perfect  free- 
dom and  force.  .  .  .  When  I  asked  him  to  write  his  name  down  he  did 
so  correctly,  but  when  I  told  him  to  write  down  what  had  happened 
to  him,  he  only  wrote  '  was,  was,  was.'  He  knew  perfectl}'-  well 
that  this  was  not  what  he  wanted  to  write,  and,  annoyed  at  not 
being  able  to  express  his  thoughts,  he  put  down  the  pen.  Two 
days  after  this,  on  my  asking  him  to  write  down  the  name  of  his 
birth-place,  he  wrote  '  alone,  alone,  alone,'  and  did  so  again  when 
I  asked  him  to  write  'good  morning.'  His  impatient  gestures,  all 
the  while,  showed  that  he  was  perfectly  conscious  that  he  was  not 
writing  what  he  had  in  his  mind.  On  the  following  day  he  wrote 
again  words  that  had  no  sense,  such  as  '  gaTiie'  for  ^  soup,'  but 
he  could  say  '  Good  morning,  Sir,'  speaking,  it  is  true,  like  a  child 
who  is  learning  to  speak.  A  few  days  later  he  said  very  distinctly, 
*  I  am  pretty  ivell,'  and  then  '  Good  7norning,  Sir,  I  am  getting  on 
well,'  with  a  hesitating  voice,  however,  like  an  habitual  stammerer, 
who  endeavours  not  to  stutter.  When  the  attempt  was  renewed 
to  make  him  write,  he  only  scribbled  on  the  paper  a  series  of 
syllables  without  any  meaning,  but  he  managed  to  write  under 
dictation,  '  I  have  eaten.'  " 

C.  Agraphia. 

6. — Damage  to  Emissive  Channels  between  the  left 
Visual  Word- Centres  and  the  Motor  Centres  in  the  corre- 
sponding Corpus  Striainm. 

In  the  typical  form  of  this  defect  there  would  be  a 
severance  of  the  connections  between  the  Visual  Word- 
Centre  and  the  superior  motor  centres  concerned  with 
the  act  of  Writing — so  that  this  act  alone  would  become 
impossible,  whilst  the  mental  powers,  with  ability  to  Read 


658        THE  CEREBRAL  RELATIONS  OF 

and  ability  to  Speak,  would  remain  intact.  This  is  a 
perfectly  possible  condition,  and  that,  too,  from  a  small 
lesion  in  one  or  other  of  various  situations.  The  lesion 
might  implicate  the  fibres  which  conduct  the  stimulus 
from  the  Visual  Word- Centre  to  the  Kinaesthetic  Word- 
Centre,  or  it  might  involve  this  latter  Centre  itself,  or, 
lastly,  it  might  destroy,  in  some  parts  of  their  course,  the 
fibres  passing  from  the  Kinaesthetic  Word- Centre  to  the 
related  motor  centres  in  the  Corpus  Striatum.  In  either 
of  these  ways  it  is  conceivable  that  a  person  might  lose 
his  ability  to  Write,  alone  and  without  other  defect. 

Should  the  individual,  however,  be  paralysed  on  the 
right  side  of  the  body  any  such  special  defect  would  be 
hidden  by  the  more  general  loss  of  power  occasioned  by 
paralysis  of  the  right  arm.  But  if  such  a  person  were 
to  attempt  to  learn  to  Write  with  the  left  hand,  there  is 
no  reason  why  he  might  not  succeed,  provided  the  left 
Visual  Word- Centre  were  itself  uninjured  and  in  free 
communication  through  callosal  fibres  with  its  fellow  of 
the  opposite  Hemisphere. 

A  person  affected  with  right  Hemiplegia  would,  however, 
probably  be  incapable  of  re-acquiring  the  art  of  Writing, 
with  the  left  hand,  if  the  left  Visual  Word-Centre  itself 
were  damaged.  But  with  the  existence  of  such  a  lesion 
the  patient  would  also  be  unable  to  comprehend  written 
or  printed  language.  This  seems  to  have  been  the  case, 
for  instance,  with  Trousseau's  patient — M.  X — ,  who, 
notwithstanding  all  his  intelligence,  could  not,  after  three 
years,  write  with  his  left  hand  (see  p.  652). 

The  Agraphic  defect  is  almost  never  met  with  alone. 
It  is  most  frequently  associated  with  some  mental  defects, 
or  with  defects  of  Articulate  Speech . 

Again,  the  same  term.  Agraphia,  may  be  appro- 
priately enough  allowed  to  include  '  incoordinate '  as  well 


Chaf.  XXIX.]  SPEECH    AND    THOUGHT.  659 

as  '  paralytic '  delects  in  the  power  of  mental  expression 
by  Writing.  Even  witli  this  extension,  however,  the  cases 
on  record  that  can  be  included  under  this  head  are  com- 
paratively few.  The  first  to  be  quoted  is  one  of  the  '  inco- 
ordinate '  type.  It  is  one  of  the  many  cases  illustrative 
of  Speech-defects  for  which  we  are'  indebted  to  Dr. 
Hughlings  Jackson.^ 

An  elderly,  healthy-looking  woman  suddenly  became  ill  five 
weeks  before  admission.  She  lost  the  entire  power  of  speech  for  a 
week,  and  was  also  paralysed  on  the  right  side.  When  seen  there 
was  no  apparent  hemiplegia,  but  she  complained  of  weakness  in 
the  right  side.  She  could  then  talk,  but  made  mistakes.  For 
instance,  when  I  was  trying  her  sense  of  smell,  which  was  very 
defective  since  the  paralysis,  she  said  in  answer  to  a  question,  "  I 
can't  say  it  so  much,"  meaning  she  could  not  smell  so  well.  She 
frequently  made  mistakes  in  speaking,  and  called  her  children  by 
wrong  names.  This  was  never  very  evident  when  she  came  to  the 
hospital,  and  might  easily  have  been  overlooked,  but  her  friends 
complained  much  of  it.  She  seemed  to  be  very  intelligent.  Her 
power  of  expression  by  luriting,  however,  was  very  had,  although 
her  penmanship  was  pretty  good,  considering  that  she  wrote  with 
the  weakened  right  hand.  She  wrote  the  following  at  the  hospital. 
I  first  asked  her  to  write  her  name — I  do  not  like,  for  obvious 
reasons,  to  give  her  real  name  for  comparison:  it  had  not, 
however,  the  slightest  resemblance  to  the  following,  in  sound  or 
spelling, — 

"  SUNNIL  SlCLAA  SaTRENI." 

When  I  asked  her  to  write  her  address,  she  wrote, — 

"  SUNESR  NUT  TS  MEB,  TINN —  LAIN.' 

Thinking  she  might  have  been  nervous  when  she  wrote  at  the 
hospital,  Dr.  Jackson  asked  her  to  bring  something  that  she  had 
written  at  home.  She  did  so,  but  the  specimen  (a  fac-simile  of 
which  he  gives)  was  not  in  the  least  better  than  what  she  had 
previously  written.  It  is  a  perfectly  meaningless  assemblage  of 
letters,  notable  only  for  the  frequent  repetition  of  small  groups  of 
them,  in  a  fashion  which  we  shall  also  find  repeated  in  the  next 
case. 

*  Lond.  Hosp.  Keports,  vol.  i.  p.  432. 


6C0  THE    CEREBRAL    RELATIONS    OF 

Unfortunately  it  is  not  stated  wlietlier  this  woman  was 
able  thoroughly  to  comprehend  written  or  printed  cha- 
racters, and  without  knowing  her  condition  in  this  respect, 
no  safe  diagnosis  can  be  made.  There  was  in  her  case 
an  ability  to  form  letters,  but  an  inability  to  group 
them  into  proper  words — and  thus  a  complete  inability  to 
express  her  thoughts  by  Writing,  even  though  her  errors 
in  Articulate  Speech  were  comparatively  few. 

The  next  case  is  one  which  came  under  the  writer's  own 
observation.  Jt  is  by  no  means  typical,  but  very  peculiar 
in  many  respects.  The  man  was  a  Criminal  Lunatic — one 
who  had  been  some  years  before  absolved  from  the  penalty 
otherwise  attaching  to  a  murderous  act,  on  the  ground 
that  he  was  an  irresponsible  agent.* 

The  patient,  originally  a  sailor,  is  now  about  45  years  of  age,  and 
partially  demented;  lie  was  formerly  violent  and  dangerous,  bub 
without  obvious  delusions,  and  was  certified  to  be  insane  in  1855. 
It  was  not  till  about  the  year  1857,  or  later,  that  he  began 
to  write  in  an  extraordinary  manner ;  previous  to  this  date  his 
letters  to  his  friends  are  stated  to  have  been  written  in  an  in- 
telligible style.  The  peculiarity  manifested  itself  first  in  this  way : 
he  commenced  the  writing  of  each  word  correctly,  and  then  in  the 
place  of  some  of  the  remaining  letters  he  wrote  Jfr/.  Afterwards, 
the  whole  character  of  the  word  became  altered,  and  duplication  of 
maijy  of  the  consonants,  together  with  an  almost  invariable  termi- 
nation with  the  letters  ndendd,  or,  at  least,  endd,  became  the  most 
noteworthy  features  of  writing  which  though  produced  volumi- 
nously was  almost  utterly  unintelligible.!  When  I  was  in  the  habit 

*  The  particulars  are  given  nearly  as  they  were  recorded  in  the 
«  Med.  Chir.  Rev."  for  Jan.,  1869. 

f  Trousseau  speaks  of  a  case  of  Aphasia  in  which  the  person 
during  recovery,  when  he  became  able  to  utter  a  few  monosyllables, 
always  ended  them  by  tif;  and  if  he  wished  to  say  a  word  of 
several  syllables,  he  only  pronounced  the  first  syllable,  and  added 
tif  to  it,  saying,  for  example,  "  montif"  for  "monsieur,"  "bontif" 
ior  "  bonjour,"  etc.  We  have  thus  additional  evidence  (^f  the  simi- 
larities existing  between  the  different  kinds  of  defective  Speech 
and  defective  Writing. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  661 

of  seeing  him,  about  three  years  ago,  he  gave  me  very  many  sheets 
of  his  peculiar  writing  at  different  times,  and  from  what  I  have 
in  my  possession  I  have  cut  out  the  sixteen  specimens  that  have 
been  lithographed.  These  show,  plainly,  that  he  either  wrote 
with  a  peculiar  and  continual  iteration  of  certain  sets  of  letters, 
the  writing  being  partly  intelligible,  or  else  that  it  was  a  mere 
succession  of  letters  or  strokes  to  which  no  meaning  whatever 
could  be  attached. 

One  of  the  principal  peculiarities  about  this  case  is,  that  whilst 
the  man  writes  in  this  fashion  he  speaks  in  the  ordinary  way. 

At  my  request  Dr.  Orange  very  kindly  submitted  the  patient  to  a 
careful  re-examination,  and  the  replies  with  which  he  has  furnished 
me  seem  to  show  that  the  man  has  now  become  more  demented, 
though  his  special  defect  is  much  less  marked  than  it  was.  The 
principal  peculiarities  observed  were  as  follows : — 

1.  He  can  speak  fairly  well  for  a  short  time,  but  his  attention 
wanders,  and  his  voice  then  becomes  drawling  and  monotonous, 
when  he  often  either  mispronounces  a  word  (generally  by  altering 
its  termination)  or  he  substitutes  another  word  or  mere  sound 
having  no  meaning. 

2.  He  can  read  the  newspaper  either  to  himself  or  aloud — but 
he  does  not  seem  to  gather  the  full  meaning  without  effort,  and  his 
power  of  continuous  effort  is  small.  When  he  reads  aloud  he 
stumbles  over  the  difficult  words,  and  he  reads  in  a  drawling  tone, 
but  the  words  which  he  utters,  if  not  actually  those  before  his  eyes, 
are  words  of  a  somewhat  similar  sound,  and  do  not  appear  to  have 
any  obvious  relation  to  the  peculiar  style  of  his  writing. 

3.  He  spells  a  word,  when  asked  to  do  so,  in  the  way  in  which 
he  would  write  it,  and  then  he  pronounces  it  correctly  immediately 
afterwards. 

It  is  interesting  to  find  that  this  man's  mode  of  Beading 
was  in  accordance  with  his  mode  of  Speaking,  rather  than 
with  his  peculiar  style  of  Writing.*  Upon  this,  in  part, 
we  base  our  view  as  to  the  nature  of  his  particular  defect, 
viz.  :  that  it  was  due  not  so  much  to  disordered  action  in 
the  Visual  Word-Centre  as  to  some  defect  in  the  emissive 

*  Though  the  reverse  obtained  in  the  case  of  the  government  clerk 
recorded  by  Dr.  Jackson  (p.  628). 
29 


662        THE  CEREBRAL  RELATIONS  OF 

channels  beyond — perhaps  in  the  part  of  the  Kinaesthetic 
Centre  concerned  with  Writing-Movements.  It  is  also  in 
harmony  with  the  view  previously  enunciated,  that  in 
reading  aloud  usually  Visual  Impressions  revive  corre- 
sponding Auditory  Impressions  of  words,  and  that  the 
stimuli  which  occasion  either  form  of  Articulate  Speech 
pass  in  the  main  from  the  Auditory  to  the  Kinaesthetic 
Word-Centres,  and  thence  to  the  Motor  Centres. 

It  is  worthy  of  note,  however,  that  in  this  case,  as  well 
as  in  others  in  which  there  has  been  defective  action  of 
the  Yisual  Word-Centre,  the  mode  of  spelling  was  almost 
entirely  harmonious  with  the  patient's  mode  of  writing 
rather  than  with  his  mode  of  speaking.  It  was,  however, 
very  strange  to  hear  a  man  when  asked  to  spell  '  cat '  say 
deliberately  *  candd,'  and  then  immediately  pronounce  the 
word  as  though  he  had  spelt  it  '  cat.' 

In  a  case  of  Agraphia  recorded  by  Dr.  William  Ogle,* 
there  was  a  grave  Amnesic  condition  as  regards  Speech, 
though  this  was  associated  with  a  greater  inability  to  Write 
than  existed  in  either  of  the  other  cases. 

"James  Simmoncls,  fifty-four  years  ot  age,  after  a  heavy  blow  on 
the  left  side  of  the  head,  seven  years  ago,  was  obliged  to  give  up 
his  work.  He  spoke  without  difficulty  or  hesitation,  but  miscalled 
tilings  strangely.  He  then  had  a  fit  one  morning,  whilst  dressing, 
which  left  him  speechless  and  hemiplegic  on  the  right  side.  For  a 
fortnight  he  could  not  speak  at  all,  though  he  was  quite  sensible. 
He  could  not  say  so  much  as  'yes'  and  'no.'  From  this  ho 
gradually  recovered,  but  always,  as  before,  miscalled  things.  .  .  . 
A  month  ago  he  had  a  second  fit,  which  left  him  with  less  power 
than  before  in  his  right  side,  but  made  little  or  no  change  in  hia 
speech." 

"  There  is  now  partial  paralysis  of"  the  right  side,  which  does  not 
prevent  his  walking.  The  facial  muscles  on  that  side  are  slightly 
affected  as  well  as  the  limbs.     His  speech  is  very  hesitating  and 

*  St.  George's  Hosp.  Keports,  1867,  p.  ]  03.  The  convenient  word 
'Agraphia'  was,  in  this  article,  first  introduced  by  Dr.  AVm.  Ogle, 


CiiAP.  XXIX.]  SPEECH    AND    THOUGHT.  663 

imperfect.  He  often  stops  suddenly,  at  a  loss  for  a  word,  and 
then  frequently  uses  a  wrong  one.  As,  for  example,  he  sub- 
stituted 'barber'  for  'doctor,'  '  two  shilling  piece'  for  'spectacles,' 
'  winkles '  for  *  watercresses,'  &c.  He  can,  however,  'pronounce 
any  word  perfectly  when  prompted.  He  says  that  he  generally 
knows  when  he  has  used  a  wrong  word,  but  not  always.'* 

"  Before  his  illness  he  wrote  a  good  hand,  and  was  above  his  lot 
as  regards  education.  Noiv  he  cannot  form  a  single  letter.  Even  with 
a  copy  before  him  he  makes  only  uncertain  up  and  down  strokes.  I 
gave  him  some  printed  letters,  and  asked  him  to  pick  out  his  name. 
After  a  long  time  he  arranged  Jicmnos.  Clearly  he  had  some 
slight  notion  of  the  letters  which  composed  his  name.  According 
to  his  wife,  before  his  illness,  he  spelt  well,  and  was  very  particular 
about  the  spelling  of  his  own  name,  which  is  one  admitting  of  many 
variations.  When  a  comf  was  before  him  he  quicJdy  picked  oat 
end  arranged  his  name  correctly.  He  can  read ;  but  he  says  that 
reading  nfakes  him  very  giddy,  and  causes  great  pain  in  the  head. 
His  general  understanding  seems  good,  and  up  to  the  average  of 
:iien  in  his  class," 

Tlie  conditions  Jhere  recorded  represent  the  remainders 
of  an  *  Aphasic '  attack.  Inability  to  spell,  i.e.,  inability 
spontaneously  to  recall  the  letters  composing  a  word,  pro- 
bably depends  in  the  main  upon  some  defect  in  the  Visual 
Word-Centre  ;  but  the  patient's  ability  to  put  the  letters 
of  his  name  together  with  a  copy,  shows  that  this 
Centre  could  act  to  some  extent.  This  is  seen  also  by 
the  statement  that  he  was  ahle  to  read  a  little — though  his 
powers  in  this  direction  were  probably  very  slight.  We 
may  conclude  that  in  this  case  the  most  severe  or  durable 
lesions  were,  therefore,  in  the  track  of  the  emissive  fibres 
from  the  left  Visual  Word- Centre — perhaps  in  the  Kinses- 
thetic  Word- Centre  itself. 

Marce  speaks  of  a  man  in  regard  to  whom  it  was 
noticed  that  he  was  able  to  write  numerals  with  much 
greater  precision  and  ease  than  ordinary  letters — a  con- 
dition which  is  not  so  singular  as  he  thought.  It  is, 
indeed,  commonly  the  case,  that  Amnesic  patients  find  lesa 


664  THE    CEREBRAL    RELATIONS    OF 

difficulty  in  recalling  the  names  of  simple  numerals  than 
of  letters  (seep.  643),  which  is  not  to  be  wondered  at  when 
we  recollect  that  these  in  all  are  nine  in  number  rather 
than  twenty-six,  and  that  the  observation  directed  to 
individual  numerals  has  always  been  of  necessity  much 
more  intent  than  the  observation  of  single  letters. 
The  degree  of  familiarity  with  a  set  of  objects  or  a  set  of 
actions  is  always  a  matter  of  great  importance  in  these 
cases  of  impaired  cerebral  power :  the  newly  acquired  or 
more  complex  acts  are  those  w^hich  first  become  impossi- 
ble, whilst  those  which  are  most  familiar  and  most  deeply 
ingrained  are  the  last  to  be  interfered  with.  Dr.  Lasegue 
knew  a  musician  completely  aphasic,  who,  being  unable 
to  speak  or  write  in  the  ordinary  way,  could,  after  hearing 
a  passage  of  music,  write  such  passage  on  paper  with 
ease. 

D.  Aphemia. 

7. — Damage  to  Emissive  Channels  between  the  Audi- 
tory  and  the  Motor  Word-Centres. 

The  conditions  now  to  be  referred  to  are  related  to  de- 
fective communications  between  the  Auditory  and  the 
Motor  Word- Centres,  in  much  the  same  way  that  those 
of  the  last  section  are  related  to  defective  communications 
between  the  Visual  and  the  Motor  Word-Centres.  With 
the  necessiiry  changes,  what  is  there  said  will  also  here 
hold  good  in  reference  to  the  situations  in  which  lesions  of 
the  Brain  may  produce  Aphemia,  with  the  addition  that  this 
particular  defect  may  also  be  produced  by  a  small  lesion 
implicating  the  lower  or  medullary  centres  for  Articulation. 

These  cases,  as  isolated  defects,  are,  like  those  of  simple 
Agraphia,  extremely  rare ;  though  one  of  a  typical  cha- 
racter has  been  recorded  by  Trousseau  (see  p.  Q>(S\}),    Simi- 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  665 

larly  they  may  or  may  not  be  associated  with  paralysis  of 
limbs,  and  they  are  also  almost  invariably  occasioned  by 
lesions  in  the  left  rather  than  in  the  right  Cerebral  Hemi- 
sphere, if  the  seat  of  damage  be  above  the  pons  Varolii : 
but  when  the  lesion  is  in  the  latter  situation,  or  in  the 
Medulla,  the  question  of  the  side  affected  becomes  a  matter 
of  indifference. 

The  nearer  the  lesion  is  situated  to  the  Auditory  Word- 
Centre  (and  therefore  to  the  Cortical  Grey  Matter),  the 
greater  is  the  likelihood  that  there  will  be  complications, 
in  the  way  of  associated  mental  defects ;  whilst,  on  the 
other  hand,  in  the  cases  in  which  the  defective  action, 
resulting  in  the  production  of  Aphemia,  is  to  be  referred 
to  a  lesion  in  the  Corpus  Striatum  or  of  the  lower  articu- 
latory  centres  in  the  Medulla,  we  may  expect  to  have  to 
do  with  mere  motor  disabilities,  as  a  result  of  which  vocal 
Speech  will  be  rendered  indistinct  or  wholly  abolished. 

Some  cases  will  now  be  given  in  illustration  of  these 
defects,  beginning  with  those  which  are  most  complex, 
and  thence  passing  on  to  others  of  great  comparative  sim- 
plicity. The  first  of  them  is  an  illustration  of  extreme 
incoordinate  defects  of  Speech,  in  combination  with  other 
abnormal  conditions.  Though  complicated  and  obscure, 
it  is  too  interesting  to  be  omitted. 

This  case  was  recorded  long  ago  by  Bouillaud.*  The 
man  did  not,  as  a  rule,  speak  in  mere  unintelligible  jargon  ; 
he  mostly  made  use  of  actual  words,  though  they  were  of 
Buch  a  kind  and  so  collocated,  as  to  have  no  resemblance  to 
what  he  ought  to  have  said.  When  readiog  aloud,  how- 
ever, he  often  uttered  nothing  but  mere  jargon, 

Lefevre,  set.  54,  after  some  extreme  mental  anxiety,  became  unable 
to  read,  write,  or  find  words  to  express  his  thoughts.  His  sensibility 
and  powers  of  movement  were  unimpaired,  and  his  general  health 
*  Traite  de  I'Encephalite,  1825,  p.  290 


6G6  THE    CEREBRAL    RELATIONS    OF 

was  pretty  good.  When  he  wished  to  reply  to  questions  that  were 
addressed  to  him,  he  made  use  of  expressi»ns  either  quite  unintel- 
ligible, or  else  having  a  meaning  quite  different  trom  that  whicih 
he  intended  to  convey.  When  questioned  as  to  his  health,  he 
replied  righbly  in  two  or  three  words;  then  in  order  to  say  that  he 
did  not  suffer  at  all  from  pain  in  the  head,  he  said,  "  Les  douleurs 
ordonnent  un  avantagey"  whilst  in  writing  he  replied  to  the  same 
question  in  this  way : — "  Je  ne  souffre  pas  de  la  tete.''  When  a  word 
such  as  famhour  was  pronounced,  and  he  was  asked  to  repeat 
it,  he  said  fromage  ;  though  he  wrote  it,  on  the  contrary,  quite 
correctly  when  asked  to  do  so.  He  was  requested  to  copy  the 
words  feuille  medlcale  ;  he  wrote  them  perfectly,  but  could  never 
exactly  read  the  words  which  he  had  just  written;  he  pronounced 
instead,  fequicale,  fenicale  and  fedocale.  Then,  when  made  to  read 
the  word  fequical,  written  by  himself,  he  pronounced  it  jardait. 
He  often  wrote  upon  paper  phrases  which  were  unintelligible, 
either  by  the  nature  of  the  words  employed,  or  by  their  lack  of 
relation  to  one  another.  When  he  was  shown  different  objects,  he 
generally  named  them  correctly;  but  then  he  was  wrong  at  times, 
and  during  the  same  sitting  he  called  "une  plume,  un  drap ;  vAi 
crachoir,  ime  'plume ;  une  main,  un  tasse  ;  une  corde,  une  main ;  une 
bague,  un  crachoir.^* 

This  case  is  complicated,  and  one  in  which  tfiere  were 
very  distinct  mental  defects.  The  Visual  Centre  seems  to 
have  been  fairly  healthy,  hence  the  patient  was  able  to  copy 
correctly.  From  the  fact,  however,  that  instead  of  repeat- 
ing the  word  *  tambour,'  when  asked,  he  said  '  fromage,' 
though  he  wrote  the  word  quite  correctly ;  and  from  the 
fact  that  after  he  had  also  copied  a  written  word  properly, 
he  could  not  rightly  pronounce  it,  we  may  infer  that  im- 
pressions received  in  the  Auditory  Word- Centre,  might 
pass  on  correctly  to  the  Visual  Word-Centre,  so  as  to 
enable  its  equivalent  to  be  correctly  reproduced  in  writing  ; 
but  that  impressions  striking  at  once  upon  the  Auditory 
Word-Centres,  or  coming  to  them  from  the  Visual  Word- 
Centres,  could  not  be  correctly  rendered  into  articulate 
speech.      The   conclusion,   therefore,    is   warranted   that 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  667 

there  was  in  this  case  not  so  much  a  defect  of  the 
Auditory  Word-Centre,  but  rather  something  wrong  with 
a  portion  of  the  emissive  channels  leading  from  it,,  by 
way  of  the  Kinsesthetic  Centres,  to  the  motor  centres 
for  Articulation — whereby  the  activities  of  the  Auditory 
Word-Centre  became  (incoordinately)  associated  with  Arti- 
culatory  Movements  of  the  wrong  kind. 

This  defect  was,  therefore,  in  its  relations  to  Speech, 
very  comparable  with  those  existing  in  relation  to  Writing, 
in  the  cases  of  Agraphia  recorded  by  Dr.  Jackson  and 
the  writer,  as  given  in  the  last  section.  The  case  was, 
however,  complicated  by  considerable  Amnesic  defects 
of  the  incoordinate  type,  showing  themselves  both 
in  Speech  and  Writing,  though  more  frequently  in  the 
former. 

In  another  very  remarkable  case,  carefully  investigated 
and  recorded  by  Dr.  Osborn,*  the  patient  was  able  to 
talk  only  in  a  meaningless  jargon,  and  on  attempting 
to  read  aloud  gave  utter  mce  also  to  a  series  of  articulate 
sounds  having  no  intelligible  meaning  or  resemblance  to 
those  which  he  should  have  uttered.  Some  of  the  prin- 
cipal particulars  concerning  this  case  are  subjoined. 

A  scholar  of  Trinity  College,  Dublin,  twenty-six  years  of  age,  of 
very  considerable  literary  attainments,  and  well  versed  in  French. 
Italian,  and  German,  whilst  sitting  at-  breakfast,  after  having 
bathed  in  a  neighbouring  lake,  suddenly  had  an  apoplectic  fit.  He 
was  reported  to  have  become  "  sensible  in  about  a  fortnight,"  but, 
although  restored  to  the  use  of  his  intellect,  he  had  the  mortifica- 
tion of  finding  himself  deprived  of  speech.  He  spoke,  but  what  he 
Baid  was  quite  unintelligible,  althougli  he  laboured  under  no  para- 
lytic affliction,  and  uttei-ed  a  variety  of  syllables  with  the  greatest 
apparent  ease.  When  he  came  to  Dublin  his  extraordinary  jargon 
led  to  his  being  treated  as  a  foreigner  in  the  hotel  where  he  stopped; 
and  when  he  went  to  the  College  to  see  a  friend  he  was  unable  to 

•  **  Dublin  Journ.  of  Med.  and  Chemical  Science,"  vol.  iv.  p.  157. 


G68         THE  CEREBRAL  RELATIONS  OF 

express  his  wish  to  the  gate-porter,  and  succeeded  only  by  pointing 
to  the  apartments  which  his  friend  had  occnpied. 

Dr.  Osborn,  after  frequent  careful  investigations,  ascertained  the 
following  particulars  concerning  his  patient : — 

1.  He  perfectly  comprehended  every  word  said  to  him. 

2.  He  perfectly  comprehended  printed  language.  He  continued 
to  read  a  newspaper  every  day;  and  when  examined  proved  that 
he  had  a  very  clear  recollection  of  all  that  he  read.  Having  pro- 
cured a  copy  of  Andral's  '  Pathology '  in  French,  he  read  it  with 
great  diligence,  having  lately  intended  to  embrace  the  medical 
profession. 

3.  He  expressed  his  ideas  in  writing  with  considerable  fluency; 
and  when  he  failed  it  appeared  to  arise  merely  from  confusion,  and 
not  from  inability,  the  words  being  orthographically  correct,  but 
sometimes  not  in  their  proper  places. 

4.  His  general  mental  power  seemed  unimpaired.  He  wrote 
correctly  answers  to  historical  questions;  he  translated  Latin  sen- 
tences a<}curately ;  he  added  and  subtracted  numbers  of  different 
denominations  with  uncommon  readiness;  he  also  played  well  at 
the  game  of  draughts. 

5.  His  power  of  repeating  words  after  another  person  ivas 
almost  confined  to  certain  monosyllables;  and  in  repeating  the 
letters  of  the  alphabet  he  could  never  pronounce  h,  q,  u,  v,  iv,  a?, 
and  z,  although  he  often  uttered  these  sounds  in  attempting  to 
pronounce  the  other  letters.  The  letter  i,  also,  he  was  very  seldom 
able  to  pronounce. 

6.  In  order  to  ascertain  and  place  on  record  the  peculiar  imper- 
fection of  language  which  he  exhibited.  Dr.  Osborn  selected  and 
laid  before  him  the  following  sentence  from  the  bye-laws  of  the 
College  of  Physicians,  viz.,  "  It  shall  he  in  the  poivcr  of  the  College 
to  examine  or  not  examine  any  Licentiate  previous  to  his  admission 
to  a  Fellowship,  as  they  shall  think  fit. ^* 

Having  set  him  to  read,  he  read  as  follows: — ^'  An  the  heivhat  in 
the  temother  of  the  trothotodoo  to  majorum  or  that  emidrate  eni 
enihrastrai  mestreit  to  Icetra  totomhreidei  to  ra  fromtreido  as  that 
hehritest.'*  The  same  passage  was  presented  to  him  a  few  days 
afterwards,  and  he  then  read  it  as  follows: — "Bemather  be  in  the 
hondreit  of  the  compestret  to  samtreis  amtreit  emtreido  and  tern- 
treido  mestreiterso  to  his  eftreido  turn  bried  rederiso  of  deid  daf 
drit  des  tresf' 

He    generally   knew    that  he   spoke   incorrectly,  although  he 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  6G9 

was  quite  unable  to  remedy  the  defect.  After  the  expiration  of 
eight  months,  however,  he  was  so  far  improved  that  he  was  able  to 
repeat  the  same  bye-law  after  Dr.  Osborn  as  follows  : — *' It  may  he 
in  the  'power  of  the  College  to  evhavine  or  not  ariatin  any  licentiate 
seviously  to  his  amission  to  a  spoloivship,  as  they  shall  thinlc  fit." 
Some  little  time  after  this  Dr.  Osborn  says  he  "  repeated  the  same 
bye-law  after  me  perfectly  well,  with  the  exception  of  the  word 
*  power,'  which  he  constantly  pronounced  prier.  He  was  also  able 
to  pronounce  all  the  letters  of  the  alphabet  except  d,  Jc,  and  c." 
He  progressed  in  this  way  under  the  directions  of  Dr.  Osborn,  who 
advised  him  to  commence  learning  to  speak  again  like  a  child, 
repeating  first  the  letters  of  the  alphabet,  and  subsequently  words, 
after  another  person,  on  the  ground  that  he  had  "lost,  not  the 
power,  but  the  art  of  using  the  vocal  organs." 

In  this  strange  hut  very  interesting  case  there  seems  to 
have  been  no  appreciable  mental  defect.  It  appears  con- 
ceivable that  a  disordered  relation  between  the  Auditory 
and  the  Kinaesthetic  Word-Centres,  or  else  a  disordered 
activity  of  the  latter  Centres  themselves,  may  have 
sufficed  to  induce  some  such  defect. 

Trousseau  records  another  interesting  case,  in  which 
there  was  an  absence  of  mental  defect  and  a  simple 
inability  to  Speak.     He  says  : — 

"I  received  one  day  in  my  consulting-room  a  carrier  of  the  Paris 
Halles,  very  young,  and  having  the  appearance  of  a  man  enjoying 
excellent  health.  He  made  signs  that  he  could  not  speak,  and 
handed  to  me  a  note  in  which  the  history  of  his  illness  was  detailed. 
Jle  had  %vritten  the  note  himself,  with  a  very  steady  hand,  and  had 
worded  it  well.  A  few  days  previously  he  had  suddenly  lost  his 
senses,  and  had  been  unconscious  for  nearly  an  hour.  When  he 
came  round  he  exhibited  no  symptom  of  paralysis,  but  could  noi 
articulate  a  single  word.  He  moved  his  tongue  perfectly,  he 
swallowed  with  ease,  but,  however  much  he  tried,  he  could  not 
utter  a  word.  He  was  ineffectually  galvanized  for  a  fortnight, 
but  without  any  special  treatment  he  completely  recovered  his 
speech  five  or  six  weeks  after  the  invasion  of  the  complaint.  It  is 
very   remarkable,  however,  that  during  the  whole  course  of  this 


670  THE    CEREBRAL    RELATIONS    OF 

singular  affection  he  could  manage  all  Ids  affairs  hy  suhstitating 
writing  for  speech. 

Here,  the  man  being  ud able  to  articulate  at  all,  was  also 
incapable  of  reading  aloud  in  any  fashion ;  although  we 
may  fairly  presume  that  he  could  readily  comprehend 
what  he  read  silently.  And  if,  as  the  writer  thinks,  the 
patient  was  suffering  from  a  simple  motor  defect,  it  was 
not  so  strange,  as  Trousseau  supposes,  that  he  should 
have  been  perfectly  well  able  to  manage  his  own  affairs. 

This  last  case  may,  indeed,  be  pretty  confidently 
interpreted  through  the  reflected  light  thrown  upon  it  by 
another,  more  recently  recorded  by  Dr.  Bristowe.* 

"A  steward  of  a  steam  packet,  set.  36,  in  the  midst  of  previously 
nninterrupted  good  health,  complained,  on  the  morning  of  March  7, 
1869,  in  the  Straits  of  Malacca,  of  headache  and  feverish ness. 
This  condition  was  succeeded,  in  the  course  of  a  few  hours,  with  a 
series  of  very  severe  epileptiform  attacks  following  one  another 
quickly.  Four  hours  after  their  commencement  he  began  to 
recover  consciousness.  When  he  recovered,  he  found  himself  lying 
on  the  floor  of  the  cabin ;  and  he  soon  discovered  that,  although 
he  could  see  and  understand  everything  that  was  going  on,  he  was 
totally  unable  to  move  a  limb,  had  entirely  lost  the  faculty  of 
speech,  and  was  'stone  deaf.'  He  could  not  hear  a  pistol  fired  off 
close  to  his  ear.  He  remained  in  this  condition  as  nearly  as 
possible  up  to  the  time  of  his  arrival  at  Singapore  on  March  20." 
At  that  time  his  right  leg  and  arm  were  still  weak,  his  left  leg 
and  arm  were  numb  and  quite  powerless.  He  had  considerable 
difficulty  in  *  masticating '  his  food,  and  he  was  still  perfectly  deaf 
and  speechless.  He  gradually  improved  in  the  Singapore  Hos- 
pital. "In  the  first  week  he  regained  the  complete  use  of  his  riyht 
side,  and  audition  so  far  returned  that  he  could  hear  when  spoken 
to  loudly.  His  hearing  was  completely  restored  by  April  22.  He 
also  regained  to  a  great  extent  the  use  of  his  left  arm,  and  improved 
remarkably  in  general  health."  He  left  the  Hospital  in  the  middle 
of  June,  and  was  put  on  board  a  sailing  vessel  homeward  bound. 

*  "  Trans,  of  the  Cliiiical  Society,"  1870,  p.  92. 


Chap.  XXIX.]  SPEECH    AND    THOUGHT.  671 

On  November  1st  he  was  admitted  into  St.  Thomas's  Hospital,  still 
speechless,  and  dragging  his  left  leg  much  in  walking. 

Dr.  Bristowe  says : — "  Three  days  after  admission  I  saw  the 
patient  for  the  first  time,  and  examined  him  pretty  carefully.  I 
found  that  he  was  perfectly  intelligent,  that  he  understood  every- 
thing that  was  said  to  him,  that  he  could  read  well  and  compre- 
hend everything  that  he  read,  and  that  he  could  maintain  a 
convereation  of  any  length,  he  writing  on  a  slate  and  his  inter- 
locutor speaking.  He  wrote  indeed  with  remarkable  facility  a  very 
excellent  and  legible  hand,  expressing  himself  with  perfect  point 
and  accuracy,  except  for  an  occasional  error  of  spelling  and  con- 
slraction,  due  evidently  to  defective  education.  But  he  could  not 
speak,  he  could  not  utter  a  single  articulate  sound.  I  ascertained, 
however,  that  he  could  perform  with  his  lips,  tongue,  and  cheeks 
all  possible  forms  of  voluntary  movement,  and  also  that  he  was 
capable  of  vocal  intonation,  in  other  words,  that  he  could  produce 
musical  laryngeal  sounds." 

This  patient  was  afterwards  taught  with  great  care,  and  with 
complete  success,  to  speak  again,  although  "  he  had  been  nine 
months  entirely  speechless,  and  believed  himself  to  be  hopelessly 
dumb." 

The  bilateral  paralysis  whicli  existed  at  first,  together 
with  complete  deafness  and  other  symptoms,  make  it  almost 
certain  that  in  this  case  the  patient  was  suffering  from  a 
lesion  situated  somewhere  on  the  confines  between  the 
upper  part  of  the  Medulla  and  the  pons  Varolii.  A  lesion 
here  might  cause  the  complete  deafness,  the  double 
paralysis,  and  for  a  time  functionally  disable  the  lower  arti- 
culatory  centres.  There  was  clearly  a  mere  motor  Speech 
defect ;  and  a  much  slighter  lesion  about  the  same  region, 
or  a  little  higher,  might  have  given  rise  to  such  minor 
symptoms  as  were  met  with  in  Trousseau's  case.  It  is 
possible,  however,  that  this  latter  group  of  symptoms  might 
have  been  occasioned  by  a  slight  lesion  higher  up  in  the 
left  motor  track — perhaps  in  the  Corpus  Striatum,  or, 
even  higher,  in  the  white  substance  intervening  between 
these  bodies  and  the  Kinaesthetic  Word- Centres. 


672    CEREBRAL  RELATIONS  OF  SPEECH  AND  THOUGHT. 

It  has  long  been  known  that  lesions  in  these  situations, 
especially  in  the  pons  Varolii,  may  cause  great  diffi- 
culties and  indistinctness  of  articulation,  if  not  actual 
loss  of  Speech.  A  briefly-related  case  of  this  kind,  in 
which  a  considerable  lesion  was  actually  found  in  this 
situation,  as  recorded  by  Dr.  Wilks,  may  suffice  for  the 
final  elucidation  of  this  section. 

"  A  lady  fell  in  a  so-called  fit  during  dinner.  She  was  taken  up 
Bpeechless  and  put  to  bed.  She  lay  with  her  mouth  open  and  with 
the  saliva  running  from  it,  and  she  was  unable  to  swallow  or  to 
siieah.  There  appeared  to  be  no  paralysis  of  her  limbs,  and  from 
her  gestures  and  expression  there  was  every  reason  to  believe  that 
she  was  perfectly  sensible.  She  was  soon  able  to  leave  her  bed, 
and  recovered  her  usual  health,  but  sJie  never  lost  the  faralysis  of 
the  tongue  and  'palate.  She  wrote  down  all  her  wants  on  a  slate. 
She  si^ allowed  with  difficulty,  and  the  saliva  was  continually  flowing 
from  her  mouth  ;  but  she  was  able  to  walk  three  or  four  miles  a  day, 
and  was  accustomed  to  join  in  a  game  of  cards.  About  two  years  after 
the  first  attack  she  had  another  apoplectic  fit,  in  which  she  died. 
On  post-mortem  examination  there  was  found  to  be  a  great  amount 
of  disease  of  the  cerebral  vessels ;  much  blood,  which  had  escaped 
from  the  pons,  was  efi'used  at  the  base.  Within  the  pons  there  was 
an  old  brownish  cyst.     The  central  ganglia  were  healthy." 

If  the  foregoing  interpretation  of  Aphemia  should 
prove  to  be  correct,  it  will  afford  a  simple  explanation 
of  a  class  of  cases  which  many  have  deemed  to  be  as 
puzzling  as  they  were  in  the  estimation  of  Trousseau. 
What  has  been  said  on  this  subject  will  have  sufficed 
to  show  their  relationship  with  those  cases  in  which 
there  is  unquestionably  a  mere  difficulty  in  articulation 
either  complicating  an  ordinary  attack  of  Hemiplegia,  or 
forming  part  of  a  degenerative  disease  of  the  Medulla, 
known  as  *  Glosso-laryngeal  paralysis'.  On  the  under- 
standing that  it  may  be  '  complete '  or  '  incomplete,' 
Aphemia  is  a  term  broad  enough  to  include  all  these  varie- 
ties of  mere  loss  of  Speech  or  difficulty  of  Articulation. 


CHAPTEE  XXX. 

FURTHER  PROBLEMS  IN  REGARD  TO  THE  LOCALIZATION  OT 
HIGHER  CEREBRAL  FUNCTIONS. 

The  study  of  the  various  defects  of  Speech,  and  of  Intellec- 
tual Expression  in  general,  produced  by  Cerebral  Disease 
is  of  great  importance  in  many  ways.  An  accumulation 
of  instances  more  or  less  crudely  observed  must  almost 
necessarily  precede  the  attempt  to  analyze  and  classify 
these  various  defects.  Thereafter  observers  will  work 
better  and  with  more  chance  of  success  in  two  directions. 
They  will  (1)  have  learned  more  fully  how  to  observe  such 
cases,  that  is,  what  is  specially  to  be  looked  for  in  the 
way  of  ability  or  defect  in  persons  so  affected ;  and  (2)  they 
may,  whenever  the  precise  mental  defects  manifested 
during  life  have  been  clearly  recognized  and  recorded,  as 
the  occasion  arises,  note  with  more  hope  of  profitabls 
scientific  result  the  exact  region  of  the  Brain  which  has 
been  damaged. 

The  error  of  massing  together  all  the  varieties  of  '  loss 
of  speech '  under  one  name,  such  as  '  Aphasia,'  and 
then  altogether  rejecting  doctrines  of  Cerebral  Localiza- 
tion, because  the  lesions  in  such  dissimilar  cases  hava 
not  always  been  found  in  some  one  part  of  the  Brain,  is 
manifest  and  absurd,  and  yet  it  is  one  which  has 
been  too  often  repeated  in  recent  years.  Even  such  an 
accomplished  physician  as  Trousseau  spoke  of  a  represen- 
tative case  of  Amnesia   as  a  typical  instance  of  Aphasia, 


G74       PROBLEMS  IN  REGARD  TO  LOCATJZATION  OP 

and  based  his  explanation  of  the  Aphasic  condition  a 
good  deal  upon  the  phenomena  by  which  it  was  charac- 
terized. This  massing  together,  under  one  name,  of 
wholly  dissimilar  defects,  and  the  confusion  thus  created, 
would  of  course,  so  long  as  it  lasted,  effectually  defeat  all 
attempts  at  Cerebral  Localization. 

It  is,  therefore,  absolutely  necessary  if  further  advance 
is  to  DC  made  in  regard  to  the  'localization  '  of  higher 
Cerebral  Functions,  first,  that  we  should  learn  carefully  to 
discriminate  the  different  Speech-defects  from  one  another 
daring  life;  and,  secondly,  that  where  opportunities  occur, 
the  locality  of  lesions  should  be  principally  observed  and 
recorded  in  typical  and  uncomplicated  cases. 

A  few  brief  additional  details  (beyond  those  which  it 
has  been  found  convenient  to  mention  in  the  last  chapter) 
will  now  be  given  as  to  the  extent  of  knowledge  already 
garnered  within  this  second  sphere  of  observation  and 
inference — which,  though  not  at  present  co-extensive  with 
the  other,  nevertheless  includes  some  facts  of  a  rather 
startling  description. 

In  1825,  Bouillaud*  affirmed  that  the  Frontal  Lobes 
of  the  Brain  were  the  parts  principally  concerned  with 
Speech,  because,  as  he  said,  these  were  the  organs  ''for 
the  formation  and  recollection  of  words,  or  the  principal 
signs  which  represent  our  ideas."  He  had  collected  114 
observations  of  disease  of  the  Frontal  Lobes  accompanied 
by  loss  or  defect  of  Speech,  and  upon  these  he  based  his 
views. 

Andral,  however,  in  1833,  recorded  fourteen  cases  where 
Speech  was  abolished  without  any  alteration  in  the  Frontal 
Lobes,  but  in  which  a  lesion  existed  in  the  Parietal  or  in 
the  Occipital  Lobes. 

*  "Traite  de  I'Eucopbalite,"  p.  284. 


CiiAP.  XXX]        HIGHER  CEREBRAL  FUNCTIONS.  67.*^ 

In  1836  Dr.  Marc  Dax  called  attention  to  the  great 
frequency  of  loss  of  Speech  in  association  with  right 
rather  than  with  left-sided  Paralysis.  The  title  of  his 
essay  was  this  : — *'  Lesions  of  the  left  half  of  the  Brain 
coinciding  with  the  loss  of  memory  of  the  Signs  of 
Thought."  *  In  support  of  this  view  that  loss  of  Speech 
depended  especially  upon  lesions  of  the  left  half  of  the 
Brain,  Dr.  Dax  brought  forward  140  observations. 

But  in  1831,  Brocaf  went  still  further.  Whilst  affirm- 
ing, with  Dr.  Marc  Dax,  that  the  left  Hemisphere  was 
the  one  principally  concerned  with  articulate  Speech,  ho 
precisely  defined  the  seat  of  lesion  in  that  condition  which 
we  now  call  Aphasia  as  "the  posterior  part  of  the  third 
frontal  convolution  of  the  left  hemisphere.'* 

This  view,  originally  based  upon  a  very  small  number 
of  cases,  was  received  at  first  with  the  greatest  surprise  and 
scepticism.  It  was  thought  by  many  to  be  most  improbable 
that  such  a  faculty  as  Speech  should  depend  upon  the  in- 
tegrity of  one  small  portion  of  only  one  of  the  two  Cerebral 
Hemispheres.  Yet  by  reason  of  the  observations  which 
have  accumulated  during  the  last  eighteen  years,  it  is  now 
admitted  by  most  of  those  who  are  best  entitled  to  judge, 
that  Broca's  localization  is  in  a  certain  sense  correct,  and 
that  in  the  instances  of  real  typical  Aphasia  the  lesion  is, 
in  a  large  majority  of  cases,  found  to  involve  the  posterior 
part  of  the  third  frontal  gyrus  on  the  left  side,  or  else  the 
immediately  subjacent  white  substance  intervening  between 
this  convolution  and  the  Corpus  Striatum.  The  reason  why 
lesions  in  other  parts  may,  according  to  their  situation, 
either  occasionally  or  invariably  lead  to  a  more  or  less 
similar  Speechless  condition,  is  a  question  upon  which  we 
shall  hope  to  throw  additional  light  in  this  chapter. 

*  Republished  in  the  "  Gaz.  Hebdomad.,"  April  28,  1865. 
f  "  Bulletin  de  la  Soc.  Anatom.,"  Aug.  and  ISTov.,  1801. 


670   PROBLEMS  IN  REGARD  TO  LOCALIZATION  OF 

Many  cases  are  on  record  in  wliich  a  lesion  of  the 
posterior  part  of  the  third  frontal  gyrus  of  the  right 
Hemisphere  has  existed,  without  producing  any  loss  of 
Speech.  So  that  we  have  both  positive  and  negative 
evidence  in  favour  of  Broca's  association  of  the  power 
of  Articulate  Speech  with  the  integrity  of  the  third  left 
ffontal  convolution,  especially  if  we  extend  the  depth  of 
the  region  cited  by  him  so  as  to  make  it  include  the 
outgoing  fibres  from  this  part  of  the  third  frontal  gyrus. 


Fia.  184.— Brain  of  a  Woman  ^-bo  fiuffered  from  Apliasia,  showing  the  traces  of 
a  lesion  in  the  posterior  part  of  the  third  frontal  Convolution.  (Prevost.)-«»'e 
"Nature,"  March  1(3,  1876,  p.  400. 


It  is,  however,  also  true  that  in  a  certain  small  pro- 
portion of  cases  a  similar  condition  of  speechlessness  has 
been  induced  where  a  lesion  has  been  found  in  the  corre- 
sponding parts  of  the  right  Hemisphere.  In  some  of 
these  exceptional  cases  the  persons  have  been  left-handed, 
though  in  others  even  this  reason  for  the  change  of 
sides  has  been  absent.  The  writer  has  himself  met  v/ith 
a  most  typical  instance  of  this.  But  it  is  of  importr.nce 
to  note  that  even  in  these  very  exceptional  cases,  though 
the  side  affected   has  been  different,   Speech  has  equally 


CuAP.  XXX.]        HIGHER  CEREBRAL  EUNCTIONS.  677 

been  lost  by  a  unilateral  damage  of  tbe  same  definite  and 
extremely  limited  region  of  the  Hemisphere. 

Thus  it  would  follow,  that  the  motor  incitations  suffic- 
ing to  call  the  articulatory  centres  into  activity  during 
Speech,  are  accustomed,  in  the  large  majority  of  cases,  to 
emerge  from  the  third  frontal  gyrus  of  the  left  side :  though 
in  a  small  minority  of  persons  it  may  happen  that  the 
effective  motor  stimuli  are  wont  to  pass  off  instead  from 
the  right  third  frontal  gyrus.  The  halves  of  the  bilateral 
Articulatory  Centres  in  the  Pons,  Medulla,  and  upper 
part  of  the  Spinal  Cord  are  so  welded  together  by  com- 
missures that  each  of  them  practically  constitutes  one  double 
Centre.  And  these  may  (after  the  manner  of  such  bilateral 
Centres)  be  incited  to  action  by  stimuli  coming  through  the 
Corpus  Striatum  either  from  the  left  or  from  the  right 
Cerebral  Hemisphere — though,  as  a  matter  of  fact,  as 
above  stated,  such  stimuli  seem  to  reach  it,  in  the  large 
majority  of  persons,  from  the  left  side  of  the  Brain. 

But  if  bilaterally-acting  muscles  are  always  in  associ^,- 
tion  with  closely  welded  bilateral  Motor  Centres,  and  if 
such  Centres  may  generally  be  called  into  activity  by 
stimuli  reaching  them  from  either  side  or  from  both  sides 
simultaneously,  then  the  habitual  excitation  of  the  Speech 
Centres  and  their  related  muscles  from  the  left  side,  must 
be  regarded  as  a  remarkable  pecuharity. 

There  is,  however,  some  reason  for  believing  that  if  the 
habitual  outgoing  channels  of  the  left  side  are  damaged 
(so  that  Speech  has  been  lost),  the  route  for  stimuli  from 
the  right  third  frontal  gyrus  to  the  corresponding  Corpus 
Striatum  may,  under  certain  circumstances,  be  more  effect- 
ively opened  up,  so  that  the  power  of  Speaking  is  after  a 
time  regained.  In  such  a  case  the  stimuli  would,  of 
course,  impinge  upon  the  right  rather  than  upon  the  left 
eide  of  the  lower  bilateral  Articulatory  Centres, 


678       PROBLEMS  IN  REGARD  TO  LOCALTZATION  OF 

Broadbent  indeed  maintains  that,  as  a  rnle,  loss  of 
Speech  is  only  temporary  with  lesions  of  the  left  Corpus 
Striatum,  or  of  those  parts  of  the  outgoing  fibres  from  the 
third  frontal  gyrus  which  are  contiguous  to  this  body.  And 
he  ingeniously  attempts  to  explain  its  supposed  speedy 
restoration  in  these  cases.  If  the  left  third  frontal  gyrus 
be  itself  undamaged,  and  if  the  fibres  of  the  Corpus 
Callosum  which  extend  from  it  to  the  right  third  frontal 
gyrus  be  intact,  then  the  outgoing  stimuli  not  being  able 
to  take  their  usual  course  may,  he  thinks,  find  their  'way 
round '  from  the  left  to  the  right  third  frontal  and  thence 
downw^ards  to  the  Corpus  Striatum  of  the  right  side.* 
In  these  cases  loss  of  Speech  would  possibly  only  exist 
for  a  few  weeks,  till  the  new  route  and  new  mode  of  action 
could  be  thoroughly  opened  up  and  established.!  It  is 
difficult,  however,  to  understand  how  the  previous  educa- 
tion and  organization  of  this  right  Corpus  Striatum  can 
have  been  brought  up  to  the  stage  necessary  to  enable  it 
speedily  to  assume  such  functions,  if,  to  take  the  most 
favourable  supposition,  only  feeble  and  ineffective  stimuli 
have  previously  been  reaching  it. 

There  are  difficulties  also  in  the  way  of  the  acceptance 
of  some  of  the  reasoning  upon  which  this  theory  is  based. 

*  Inability  on  the  part  of  an  Aphasic  person  to  learn  to  Speak 
from  the  right  side  of  the  Brain  would  thus  be  found  to  depend 
upon  couditions  precisely  analogous  to  those  producing  in  a  right- 
sided  Hemiplegic  an  inability  to  learn  to  Write  with  the  left  hand 
{i.e.,  from  the  right  side  of  the  Brain).  Speech  would  be  impos- 
sible if  the  Auditory  Centre,  and  Writing  would  be  impossible  if 
the  Visual  Centre,  in  the  left  Hemisphere  were  destroyed;  or, 
eimilar  disabilities  would  exist  if  the  fibres  of  the  Corpus  Callo- 
sum respectively  connecting  either  of  these  left  Centres  with  its 
corres[)onding  Centre  of  the  opposite  Hemisphere  were  cut  across 
by  disease. 

t  "  Brit.  Med.  Jrnl,"  April  8, 1876,  p.  435. 


CiiAP.  XXX.]        HIGFIER  CEREBRAL  FUNCTIONS.  G79 

Broadbent  says: — *'In  its  first  attempts  to  talk  the  child 
is  influenced  by  imitation  and  guided  by  the  ear  ;  that  is, 
as  the  grouping  of  the  motor  cells  of  the  cord  is  effected 
through  the  sensory  cells,  by  cell  processes  passing  from 
the  posterior  to  the  anterior  nerve  nuclei,  so  the  grouping 
of  the  cells  in  the  corpus  striatum  will  be  effected  through 
the  cells  of  the  auditory  perceptive  centre  by  means  of  the 
fibres  connecting  together  the  two.  .  .  .  And,  as  the 
motor  nuclei  of  the  cord  can  still  be  employed  in  reflex 
action  through  the  sensory  nuclei,  as  well  as  in  voluntary 
motion  by  means  of  descending  fibres  from  the  corpus 
striatum,  so  may  the  loord  groups  in  the  corpus  striatum 
be  reached  imitatively  through  the  auditory  perceptive 
centre,  as  well  as  through  the  third  frontal  gyrus.*'  Con- 
sequently he  assumes  that  there  is  a  double  action  of  a 
consensual  character  from  both  Auditory  Centres,  and  that 
in  the  early  '  imitative '  Speech-processes  these  parts  would 
both  react  upon  their  respective  Corpora  Striata.  There 
is  also,  as  he  thinks,  a  higher  or  volitional  unilateral 
action  through  the  left  third  frontal  gyrus — an  action 
which  is  unilateral  because,  as  he  puts  it,  "  The  left 
hemisphere  alone  is  educated  for  intellectual  expression." 

But,  Sensori-motor  and  Ideo-motor  acts  of  Speech  are 
dependent  upon  processes  occurring  (in  a  slightly  different 
manner)  in  identically  the  same  cerebral  regions — and  these 
would  correspond  with  Broadbent's  *  imitative  '  modes  of 
Speech.  Yet,  as  the  writer  has  previously  endeavoured  to 
show  (pp.  550-557),  no  valid  demarcation  can  be  estab- 
lished between  Ideo-motor  and  Voluntary  acts  of  Speech, 
and  the  distinction  conferred  upon  the  latter  by  the 
addition  of  an  *  emotion  of  desire '  docs  not  make  it  the 
less  necessary  for  the  outgoing  stimulus  primarily  to 
pass  off  from  the  Auditory  Centre ;  nor,  on  the  other 
hand,  is  there  any  distinct  evidence    to  show  that  the 


680   PROBLEMS  IN  REGARD  TO  LOCALIZATION  OF 

incitations  in  '  imitative  '  Speecli  do  not,  like  those  in 
Voluntary  Speech,  also  find  their  '  way  out '  through  the 
third  frontal  gyrus.  In  fact,  we  have  every  reason  to 
believe  that  the  route  from  the  Auditory  Perceptive  Centre 
to  the  Corpus  Striatum  is  one  and  the  same  for  every 
kind  of  Speech,  whether  its  mode  of  in  citation  may  be 
strictly  'imitative,'  Ideo-motor,  or  distinctly  Volitional. 

This  latter  conclusion  is  found  to  be  in  accordance 
with  the  evidence  derived  from  disease.  No  fact  has  been 
more  certainly  established  in  regard  to  Aphasic  patients, 
than  that  there  is  in  them  a  loss  not  only  of  Voluntary, 
but  of  Ideo-motor,  and,  to  just  as  marked  an  extent,  a 
loss  of  '  imitative '  Speech.  A  really  Aphasic  patient 
cannot  copy  the  simplest  word  or  vowel  sound,  which  he 
has  just  heard,  nor  does  he  even  do  it  unbidden  and  echo- 
like, in  the  most  purely  imitative  reflex  style. 

Others  again  have  assumed  that  a  separate  route  exists 
by  which  Emotional  stimuli  may  be  transmitted  to  the 
lower  centres  for  Articulation  in  the  Pons  and  Medulla, 
without  passing  through  the  Corpus  Striatum,  simply 
because  Aphasic  patients  occasionally  utter  new  words  of 
an  interjectional  order — as  oaths,  or  such  phrases  as  'Oh 
dear!'  'Thanks!'  and  other  simple  exclamations,  under 
the  influence  of  a  strong  emotional  stimulus.  Even  for 
this  kind  of  connection,  however,  no  independent  evidence 
exists  (see  p.  580) ;  and  perhaps  the  facts  can  be  equally 
well  explained  by  the  supposition  that  Emotional  stimuli 
of  greater  energy,  or  which  emanate  from  a  wider  area, 
may  occasionally  force  their  way  through  damaged  tracks, 
the  resistance  in  which  could  not  be  overcome  by  mere 
Volitional  stimuli. 

As  to  the  causes  which  have  determined  the  greater  or 
almost  exclusive  influence  of  the  left  Hemisphere  in 
inciting    Speech-movements,    only    conjectures    can    be 


CiiAP.  XXX.]        HIGHER  CEREBRAL  FUNCTIONS.  681 

offered.  It  has  been  thought  that  a  certain  more 
forward  condition  of  development  of  the  left  hemisphere 
— as  a  result  of  hereditary  right-handedness  recurring 
through  generation  after  generation — might  gradually 
become  sufficient  to  cause  the  left  Hemisphere  to  *  take 
the  lead '  in  the  production  of  Speech-movements.  Some 
little  evidence  exists — though  at  present  it  is  very  small 
— to  show  that  it  is  left-handed  people  more  especially 
who  may  become  Aphasic  by  a  lesion  of  the  right  third 
frontal  gyrus.  It  is  practically  certain,  indeed,  that  the 
great  preponderance  of  right-hand  movements  in  ordinary 
individuals  must  tend  to  produce  a  more  complex  organ- 
ization of  the  left  than  of  the  right  Hemisphere,  and  this 
both  in  its  sensory  and  its  motor  regions.  We  may  con- 
fidently look  for  the  existence  in  it  of  the  organic  basis 
of  a  vastly  greater  and  more  complex  Tactile  experience ; 
and  as  movements  of  the  right  arm  and  hand  are  more 
frequent,  both  as  associated  factors  of  this  experience 
and  in  other  ways,  we  have  also  a  right  to  expect  that  the 
Kinesthetic  Centres  will  be  similarly  developed  to  a 
notably  greater  degree  in  the  left  Hemisphere.  And  as  a 
matter  of  course  also  the  nervous  mechanisms  for  the 
movements  with  which  these  sensory  impressions  are 
associated  would  be  much  more  complex  in  the  Motor 
Ganglion  of  the  left  than  in  that  of  the  right  Hemisphere. 
Many  years  ago,  moreover,  the  waiter  ascertained  a  fact 
which  at  the  time  seemed  very  difficult  to  understand — 
viz.,  that  the  specific  gravity  of  the  cortical  Grey  Matter 
of  the  Brain  in  left  frontal,  parietal,  and  occipital  regions 
is  often  distinctly,  though  slightly,  higher  than  that  from 
corresponding  regions  of  the  right  Hemisphere.*  But 
Buch  an  increase  in  specific  gravity  might  be  produced  by 

*  See  a  paper  "  On  the  Specific  Gravity  ot  the  Human  Brain," 
in  "  Jrnl.  of  Mental  Science,"  18G6,  pp.  28,  32. 


682   PROBLEMS  IN  REGARD  TO  LOCALIZATION  OF 

the  existence  of  the  greater  number  of  cells  and  commis- 
sural fibres  which  the  extra  sensory  and  derivative  func- 
tions above  referred  to  would  probably  entail.* 

Having  considered  some  of  the  questions  of  cerebral 
localization  '  relating  to  the  production  of  Apheniia, 
Agraphia,  and  Aphasia,  something  must  now  be  said  in 
regard  to  the  seat  of  lesions  productive  of  the  very  varied 
conditions  comprised  under  the  term  Amnesia. 

Our  knowledge  on  this  point  is  at  present  rather  vague 
and  indefinite,  since  it  is  only  quite  recently  that  the 
necessity  of  not  confounding  such  cases  v/ith  Aphasia  has 
been  at  all  generally  recognized.  Moreover,  no  distinct 
attempt  has  hitherto  been  made  to  analyze  and  classify 
the  various  conditions  comprised  under  this  one  term 
*  Amnesia.'  Much  more  will  doubtless  soon  be  a^^cor- 
tained,  in  reference  to  this  subject,  by  future  workers, 
especially  when  the  examination  of  cases  is  more 
thoroughly  and  systematically  undertaken.! 

Still  the  knowledge  we  possess  of  Amnesic  conditions, 
as  well  as  of  the  distribution  of  '  ingoing '  fibres  in  their 
passage  from  the  base  of  the  Brain  to  the  Convolutions, 
already  enables  us  to  point  roughly  to  the  neighbourhood 
in  which  lesions  or  injuries  would  be  likely  to  produce 
defects  of  Speech  and  Writing  of  this  type. 

Lesions  of  the  convolutions  about  the  posterior  extremitij 

*  See  also  pp.  390-404 

t  In  all  cases  of  Amnesia,  or  of  mixed  Aphasia  and  Amnesia, 
details  should  among  other  things  always  be  given  in  reference  to 
the  following  points : — (1)  The  patient's  ability  to  understand 
spoken  words  (not  being  deaf);  (2)  to  repeat  soands  or  words  whea 
requested ;  (3)  to  write  from  dictation ;  (4)  to  understand  and 
therefore  to  point  out  printed  letters  and  words  {not  being  blind); 
(5)  to  copy  written  words,  or  printed  words  into  written  words; 
and  (6)  to  name  printed  letters  or  objects,  or  read  aloud. 


Chap.  XXX.]        HIGHER  CEREBRAL  FUNCTIONS.  683 

of  the  Sylvian  Fissure  of  the  left  Hemisphere  will  pro- 
bably prove  almost  as  instrumental  in  producing  one  or 
other  variety  of  Amnesia,  as  lesions  of  or  about  the  third 
left  frontal  are  of  inducing  Aphasia.  In  Broadbent's  caso 
(p.  645)  the  lesion  was  found  in  this  region,  and  in  a 
fairly  typical  unpublished  example  of  Amnesia  the  writer 
has  also  recently  found  a  lesion  in  the  same  situation. 

The  reason  for  looking  to  this  region  will,  moreover,  be 
obvious  if  the  reader  will  recollect  that  the  posterior  third 
of  the  peduncular  fibres  (that  is  of  the  so-called  '  internal 
capsule  ')  spread  out  from  beneath  the  posterior  part  of  the 
Thalamus  ;  and  that,  stretching  backward  and  outwards 
across  the  floor  of  the  lateral  ventricle  from  near  the  begin- 
ning of  the  descending  cornu,  they  distribute  themselves  in 
the  main  to  the  Occipital  and  the  Temporal  Convolutions. 
And  if  the  conclusions  of  Ferrier  in  regard  to  the  im- 
portant relations  of  the  *  supra-marginal  lobule '  and 
the  *  angular  gyrus '  with  the  Visual  Centre,  and  of  the 
posterior  part  of  the  *  upper  temporal  convolution  '  with 
the  Auditory  Centre  should  prove  to  be  correct,  there 
would  be  these  still  more  precise  reasons  for  expecting 
to  find  the  lesions  productive  of  Amnesia,  with  some 
frequency,  in  or  about  the  situation,  indicated.  Such  a 
*  localization  '  may,  therefore,  be  provisionally  entertained, 
and  no  more  promising  means  of  ultimately  ascertaining 
with  tolerable  certainty  the  situation  of  the  most  impor- 
tant parts  of  the  Visual  and  Auditory  Perceptive  Centres 
in  man  would  seem  to  present  themselves,  than  the  careful 
clinico-pathological  study  of  typical  Amnesic  cases  when- 
ever the  opportunities  may  occur. 

Another  question  of  great  interest  now  arises,  and  that  is, 
whether  it  will  be  found  that  lesions  productive  of  Amnesia 
are  also  in  the  main  limited  to  the  left  Hemisphere.  Some 
eminent  observers,  such  as  Brown- Sequard  and  Hugh- 


684   PROBLEMS  IN  REGARD  TO  LOCALIZATION  OF 

lings  Jackson,  believe  that  a  limitation  of  this  kind  does 
obtain.  But  whilst  the  writer  freely  admits  that  lesions 
of  the  left  are  more  likely  to  be  potential  than  those  of 
the  right  Hemisphere  in  the  production  of  such  states,  it 
seems  to  him  that  both  facts  and  theory  tend  to  negative 
the  idea  that  similar  defects  would  not  be  induced  by 
lesions  in  certain  parts  of  the  right  Hemisphere. 

It  will  be  found  that  many  such  cases  are  already  on 
record — one  of  the  most  typical  being  that  of  Marcou, 
as  given  by  Trousseau  (see  p.  621).  And  if  we  bear  in 
mind  that  corresponding  Perceptive  Centres  in  the  two 
Hemispheres  are  almost  habitually  called  into  simul- 
taneous activity,  and  are  in  structural  continuity  with 
one  another  through  the  Corpus  Callosum,  it  might  be 
expected  that  irritative  or  destructive  lesions  of  the 
Auditory  or  the  Visual  Word-Centres  of  the  right  side 
could  scarcely  occur  without  producing  distinct  derange- 
ment, at  all  events  for  a  time,  in  the  functional  activity 
of  the  similar  centres  in  the  left  Hemisphere — which, 
as  one  is  bound  to  admit,  seem  to  take  the  lead 
in  the  expression  of  Thought  by  Speech  and  Writing. 
On  this  very  interesting  subject  much  further  information 
is  needed,  and  we  have  previously  (p.  493)  had  to  refer 
to  the  doubt  that  exists  as  to  the  extent  to  which  one 
Hemisphere  alone  may  suffice  for  ordinary  mental  activity. 
It  may  fairly  be  expected,  perhaps,  that  Amnesia  produced 
by  a  lesion  of  the  right  side  would  have  a  tendency  to  be 
more  temporary  than  such  a  condition  when  occasioned  by 
similar  lesions  of  the  left  Hemisphere. 

Finally,  another  consideration  of  some  importance  in 
connection  with  *  cerebral  localizations '  now  suggests 
itself.  The  condition  of  Amnesia  may  merge  by  insensible 
gradations  into  one  of  Aphasia — so  that  the  latter  state, 
with    certain    extra    peculiarities,   may   at    times    result 


Chap.  XXX.]       HIGHER  CEREBRAL  FUNCTIONS.  685 

from  a  lesion  altogether  away  from  the  third  left  frontal 
gyrus,  if,  as  we  at  present  suppose,  the  regions  in  which 
lesions  have  the  greatest  tendency  to  produce  one  or 
other  of  the  forms  of  Amnesia  should  be  situated  around 
the  posterior  extremity  of  the  left  Sylvian  Fissure. 

This  may  be  easily  understood.  Suppose  a  person  to 
be  suflering  from  a  defective  activity  of  the  Auditory  Word- 
Centre,  so  that  Names  cannot  be  recalled  '  voluntarily '  or 
by  '  association.'  There  would  already  be  great  hesita- 
tions and  difficulties  in  the  expression  of  Thoughts,  both 
in  Speech  and  in  Writing.  But  suppose  this  mere  defec- 
tive activity  to  be  replaced  by  actual  destruction  of  the 
left  Auditory  Word-Centre,  so  that  its  functional  activity 
became  entirely  lost :  words  could  then,  of  course,  neither 
be  recalled  *  voluntarily '  nor  by  '  association  ' ;  and  still 
further,  they  could  not  be  perceived  and  consequently  could 
not  be  imitated.  An  individual  thus  affected  would  neither 
be  able  to  Speak  nor  to  Write,  that  is,  he  would  be  com- 
pletely Aphasic — with  the  superadded  peculiarity  that  he 
would  not  readily  comprehend  spoken  and  perhaps  written 
Language.  The  latter  ability  might  persist  to  some  extent, 
because  the  molecular  equilibrium  of  the  Auditory  Word- 
Centre  and  of  the  related  Visual-Centre  of  the  opposite 
Hemisphere  might  not  be  sufficiently  disturbed  to  prevent 
all  apprehension  of  spoken  or  of  written  symbols..  We 
might,  in  fact,  have  in  such  a  case,  the  production  of  a 
complex  Aphasic  condition  almost  precisely  similar  to  that 
met  with  in  the  girl  whose  case  w^as  recorded  by  Bazire, 
(p.  653)  or  even  one  like  that  recorded  by  the  writer  at 
p.  655,  and  yet  such  an  Aphasic  condition  might  have 
been  caused  by  a  lesion  far  aw  ay  from  the  left  third  frontal 
convolution.  And  if  this  were  so,  such  cases  might  have 
been  quoted  with  much  apparent  effect  against  existing 
doctrines  in  regard  to  '  cerebral  localization.' 
30 


686   PROBLEMS  IN  REGARD  TO  LOCALIZATION  OP 

Similarly,  it  is  possible  that  Agraphia,  accompanied 
by  'word-blindness,'  might  result  from  a  lesion  of  the 
left  Visual  Word-centre,  and  that  the  site  of  such  lesion 
might  be  contiguous  to  the  posterior  extremity  of  the  left 
Sylvian  Fissure. 

Aphemia  (that  is,  mere  loss  of  Speech)  could  not  be 
produced  by  a  lesion  of  this  region  of  the  Brain,  because 
destruction  of  the  Auditory  Word-centre  would  destroy 
the  revival  of  words  for  spontaneous  Writing,  as  well  as 
for  Speech — so  that  the  double  condition  Aphasia  (or 
an  approximate  state  in  which  *  imitative  '  Writing  only 
is  possible),  would  necessarily  result,  instead  of  the  more 
special  Aphemic  state. 

It  is  clear,  also,  that  if  important  tracts  of  the  Auditory 
and  Visual  Word- Centres  are  in  reality  situated  somewhere 
about  the  end  of  the  Sylvian  Fissures,  and  if  the  Kin- 
aesthetic  Word- Centres,  both  for  Speech  and  Writing,  are 
situated  in  or  somewhere  in  the  neighbourhood  of  the 
third  frontal  convolutions.  Aphasia  might  in  addition 
be  caused  by  lesions  cutting  across  the  commissural 
fibres  in  any  part  of  their  course  between  these  pairs 
of  centres. 

Clearly,  if  stimuli  caused  by  the  mental  revival  of 
words  do  not  (a)  issue  from  the  Auditory  and  Visual 
Word-Centres  ;  if  they  (b)  are  stopped  on  their  way  there- 
from to  the  corresponding  Kinesthetic  Word-Centres;  or 
(c)  if  they  are  stopped  in  or  on  the  other  side  of  these  latter 
Centres,  that  is  on  their  way  to  the  left  Corpus  Striatum, 
the  result  would,  in  each  case,  be  the  production  of  Aphasia, 
although  the  situations  of  the  lesions  in  these  cases  would 
be  altogether  difierent.  In  the  first  case,  too,  we  should 
have  Aphasia  with  much  mental  impairment ;  in  the 
second  case  we  should  have  Aphasia  with  trifling  mental 
impairment ;  whilst  in  the  third  case  we  should  have  the 


Chap.  XXX.]        HIGHER  CEREBRAL  FUNCTIONS.  637 

typical  Aphasia,  in  wliich  little  or  no  mental  degradation 
is  to  be  detected. 

This  being  true,  a  general  law  may  provisionally  be 
formulated,  as  a  future  working  hypothesis  :  that  the  ten- 
dency to  mental  impairment  ivith  Afhasia,  and  the  degree  of 
such  impairment,  ivill,  other  things  being  equal,  increase 
as  lesions  of  the  left  Hemisphere  recede  in  site  from  the 
*  third  frontal  convolution^  and  approach  the  Occipital  Lobe, 
The  general  doctrine  of  Marc  Dax  seems  to  be  justified, 
whilst  Broca's  more  special  localization  must  be  held  to 
hold  good  only  for  one  particular  though  very  common 
form  of  Loss  of  Speech — or,  to  use  the  broader  and  more 
accurate  phraseology,  loss  of  the  power  of  Intellectual 
Expression. 

The  conclusions  above  arrived  at  are  found  to  afford  a 
new  and  quite  un looked  for  confirniation  of  the  view 
already  announced  as  to  the  special  frequency  with  wliich 
lesions  of  the  Occipital  Eegions  of  the  Hemisphere  are 
apt  to  be  associated  with  marked  mental  degradation  ;  they 
will  also  tend  to  make  us  appreciate  more  fully  the  real 
validity  of  the  objections  raised  by  some  against  the 
doctrine  that  the  posterior  part  of  the  left  '  third  frontal 
gyrus  '  is  the  region  always  damaged  in  cases  of  Aphasia  ; 
and  they  may  pave  the  way  for  new  and  more  exact 
differential  observations,  by  means  of  which  alone  we  can 
expect  to  make  real  progress  in  a  task  of  extreme  diffi- 
culty, in  which  we  are  now  only  breaking  ground  in  a 
tentative  manner — that  is,  in  the  endeavour  to  determine 
what  kind  of  functions  are  principally  carried  on  in  differ- 
ent regions  of  the  Cerebral  Cortex. 

If  we  have  said  nothing  in  regard  to  the  '  localization  * 
of  certain  higher  Intellectual  and  Moral  Powers,  the  reason 
for  this  will  be  obvious  to  all  thoughtful  readers.     No  step 


688       PROBLEMS  IN  REGARD  TO  LOCALIZATION  OF 

can  be  taken  with  any  chance  of  success  in  this  direction 
till  the  preliminary  enquiries  to  which  we  have  been 
devoting  our  attention  have  been  reduced  to  a  more  settled 
condition.  The  foundations  of  the  subject  must  clearly 
be  laid  before  we  can  begin  to  rear  a  superstructure. 

Yet  that  every  higher  Intellectual  and  Moral  Process — -just 
as  much  as  every  lower  Sensorial  or  Perceptive  Process- 
involves  the  activity  of  certain  related  cell  and-fibre  net- 
works in  the  Cerebral  Cortex,  and  is  absolutely  dependent 
upon  tlie  functional  activity  of  such  networks,  the  writer 
firmly  believes.  He,  however,  as  decidedly  rejects  the 
notion  which  some  would  associate  with  such  a  doctrine, 
viz.,  the  supposition  that  Human  Beings  are  mere  '  Con- 
scious Automata.' 

It  must  be  conceded  that  if  Conscious  States  or  Feelings 
have  in  reality  no  bond  of  kinship  with  the  molecular 
movements  taking  place  in  certain  Nerve  Centres ;  if  they 
are  mysteriously  appearing  phenomena,  differing  absolutely 
from,  and  lying  altogether  outside,  the  closed  *  circuit  of 
motions '  with  which  they  coexist,  no  way  seems  open  by 
which  such  Conscious  States  could  be  conceived  to  affect 
or  alter  the  course  of  such  Motions.  The  logic  of  this 
seems  irresistible.  The  conclusion  can,  indeed,  only  be 
avoided  by  a  repudiation  of  the  premises  :  and  this  the 
writer  does.  He  altogether  jejects  the  doctrine  that  there 
is  no  kinship  between  States  of  Consciousness  and  Nerve 
Actions,  and  consequently  would  deny  the  view  that  the 
'causes'  of  Conscious  States  lie  altogether  outside  the  cir- 
cuits of  Nerve  Motions. 

Consciousness  or  Feeling  must  be  a  phenomenon  having 
a  natural  origin,  or  else  it  must  be  a  non-natural,  non- 
material  entity.  For  reasons  which  have  been  set  forth 
in  various  parts  of  the  present  volume  the  writer  adopts 
the  former  of  these  views. 


C.iAP.  XXX.]    HIGHER  CEREBRAL  FUNCTIONS.        6S9 

It  is  commonly  believed  that '  living  matter  '  has  now,  or 
has  had  in  past  times,  a  natural  origin  ;  Nerve  Tissues  also 
have  a  natural  origin  in  or  from  elemental  forms  of  '  living 
matter';  and  if  Conscious  States  or  Feelings  are  admitted 
to  be  an  appanage  only  of  Nerve  Actions,  so  also  (as  far  as 
we  can  ascertain)  does  their  mode  of  appearance,  their  in- 
crease in  intensity,  their  modifiability  by  agents  modifying 
the  nerve  tissues,  and  the  limitation  by  which  they  occur 
only  in  association  with  certain  nerve  actions  taking  place  in 
the  higher  and  most  complex  of  an  animal's  Nerve  Centres, 
harmonize  with  the  notion  that  they  are  in  some  way  an 
actual  outcome  of  such  Nerve  Actions — -no  more  capable 
of  being  dissevered  from  the  physical  conditions  on  which 
they  depend,  than  is  Heat  to  be  dissevered  from  its  physi- 
cal conditions  (see  p.  142).  To  say  that  Heat  is  a  '  mode  of 
motion,'  takes  for  granted  the  underlying  fact  that  wo  can- 
not have  motion  except  through  a  something  which  moves. 
Heat  has  no  abstract  and  isolated  existence  as  an  entity. 
Consciousness  also  is  a  result  of  a  something  which  moves. 
But  just  as  it  is  the  very  material  motions  on  which  Heat 
depends  which  do  the  work  ascribed  to  Heat,  so  do  the 
very  material  motions  on  which  Consciousness  or  Feeling 
depends,  do  the  work  which  we  ascribe  to  Feeling.  These 
particular  motions,  be  it  remarked,  enter  as  components 
into  the  '  circuit  of  motions  '  constituting  Nerve  Actions, 
and  may,  therefore,  easily  co-operate  as  real  motors. 
Hence  it  is  that  States  of  Feeling  may,  in  very  truth, 
and  in  accordance  with  popular  belief,  react  upon  Nerve 
Tissues  so  as  to  alter  the  molecular  motions  taking  place 
therein.  Feelings,  whether  purely  personal  or  of  the 
moral  order,  thus  have,  as  they  seem  to  have,  an  indubi- 
table effect  in  modifying  our  Intellectual  Operations,  our 
Volitions,  or  our  Movements. 

To  show  how  these  particular  motions  in  Nerve  Tissue 


690   PROBLEMS  IN  EEGaRD  TO  LOCALIZATION. 

arise  which  underlie  Conscious  States,  and  how  they  again 
subside  into  more  ordinary  nerve  actions,  roust,  from  the 
very  nature  of  the  problem,  ever  remain  impossible.  But 
we  certainly  should  not  on  this  account  allow  ourselves  to 
be  mentally  paralysed  by  a  belief  in  the  existence  of  a 
metaphysical  gulf  between  what  is  termed  the  Subjec- 
tive and  the  Objective — the  '  Ego  '  and  the  *  Non-Ego.* 
Yet,  even  some  believers  in  the  philosophy  of  evolution 
have  thus  been  led  to  deny  the  natural  origin  of  Con- 
scious States,  and  have  as  a  consequence  found  them- 
selves forced  to  hold  a  doctrine  of  thoroughgoing  '  Auto- 
matism ' — one  in  which  all  notions  of  Free  Will,  Duty, 
and  Moral  Obligation  would  seem  from  this  theoretical 
basis  to  be  alike  consigned  to  a  common  grave,  together 
with  the  underlying  powers  of  self-education  and  self- 
control. 


APPENDIX. 


VIEWS  CONCERNING  THE  EXISTENCE  AND  NATURE 
OF   A   MUSCULAR    SENSE*. 

According  to  Sir  William  Hamilton,  the  recognition  of  the  Mus- 
cular Sense,  as  a  medium  of  apprehension,  was  originally  made, 
some  three  centuries  ago,  by  two  Italian  physicians  It  was  recog- 
nized by  Julius  CfBsar  Scaliger  in  1557,  and  afterwards  indepen- 
dently by  Cassalpinus  of  Arezzo  in  1569,  that  the  exercise  of  our 
power  of  movement  is  the  means  whereby  we  are  enabled  to  esti- 
mate degrees  of  *  resistance,'  and  that  by  a  faculty  of  '*  active 
apprehension  "  which  was  by  them  contrasted  with  touch  as  "  a 
capacity  of  sensation  or  mere  consciousness  of  passion." 

After  a  very  long  interval,  De  Tracy  (one  of  the  most  distinguished 
followers  of  Condillac)  about  the  beginning  of  this  century,  more 
explicitly  developed  this  conception  and  "  established  the  distinc- 
tion between  active  and  jdassive  touch."  German  physiologists 
and  psychologists  towards  the  close  of  the  last  and  the  beginning 
of  this  century  had,  however,  made  the  same  analysis,  and  "the 
active  touch  there  first  obtained  the  distinctive  appellation  of  the 
Muscular  Sense  (Muskelsinn)."  These  views  were  soon  after  in- 
troduced into  Scotland  by  Dr.  Thomas  Brown. 

Subsequent  variations  of  opinion  in  regard  to  the  Muscular  Sense 
are,  to  some  extent,  represented  by  the  following  quotations.  J. 
Miiller  ("  Physiologic,"  1835)  says: — *'  We  have  a  very  exact  notion 
of  the  quantity  of  nerve  force  starting  from  the  brain,  which  is  neces- 
sary to  produce  a  certain  movement  .  .  .  .  It  would  be  very  possible 
that  the  appreciation  of  the  weight  and  pressure,  in  cases  where 
we  raise  or  resist,  should  be,  in  part  at  least,  not  a  sensation  in  the 
muscle,  but  a  notion  of  the  quantity  of  nerve  force  which  the  brain 
is  excited  to  call  into  action."  Soon  after  this  date,  we  find  Sir 
William  Hamilton  (1846),  in  his  '  Notes  and  Dissertations '  on  Reid, 
*  See  p.  5-11. 


692  APPENDIX. 

maintaining  that  tlie  notion  of  'resistance'  or  'weight'  is  appre- 
hended "through  the  locomotive  fdculty  and  not  the  muscular 
sense."  His  view  was  almost  precisely  similar  to  that  of  Miiller; 
for  whilst  holding  that  resistance  and  weight  are  measured 
principally  by  what  he  terms  the 'locomotive  faculty,' he  admits 
that  the  appreciation  by  this  faculty  of  the  greater  or  less  force  of 
our  "  mental  motive  energy  "  is  always  accompanied  and  aided  "  by 
sensations,  of  which  the  muscular  nisus  or  quiescence,  on  the  one 
hand,  and  the  resisting,  the  pressing  body,  on  the  other,  are  the 
causes."  He  adds : — "Of  these  sensations, the  former, to  wit, the  feel- 
ings connected  with  the  states  of  tension  and  relaxation, lie  wholly  in 
the  muscles,  and  belong  to  what  has  sometimes  been  distinguished  as 
the  muscular  sense.  The  latter,  to  wit,  the  sensations  determined 
by  the  foreign  pressure,  lie  partly  in  the  skin,  and  belong  to  the 
sense  of  touch  proper  and  cutaneous  feeling,  partly  in  the  flesh, 
and  belonging  to  the  muscular  sense.  These  affections,  sometimes 
pleasurable,  sometimes  painful,  are,  in  either  case,  merely  modifica- 
tions of  the  sensitive  nerves  distributed  to  the  muscles  and  to  the 
skin." 

This  opinion  that  we  appreciate  *  weight  *  or  '  resistance  '  prin- 
cipally by  the  so-called  '  locomotive  faculty '  was,  a  little  later,  also 
favourably  regarded  by  Ludwig,  who  says  ('Lehrb.  der  Physiologic,' 
1852) : — "  It  is  conceivable  and  not  unlikely  that  all  knowledge 
and  discrimination  arrived  at  through  the  exertion  of  the  voluntary 
muscles  are  attained  directly  through  the  act  of  voluntary 
excitation,  so  that  the  effort  of  the  will  is  at  once  proceeded  on  as 
a  means  of  judgment."  Prof  Bain,  in  the  first  edition  of  his 
work,  "The  Senses  and  the  Intellect"  (1855),  seemed  to  incline  to 
the  same  view,  though  his  opinion  was  not  quite  adequately  ex- 
pressed. He  demurs  to  what  he  calls  Hamilton's  assumption  that 
*'  we  have  a  feeling  of  the  state  of  tension  of  a  muscle,  indepen- 
dently of  our  feeling  of  motive  power  put  forth."  "It  may  be 
quite  true,"  he  adds,  "that  sensitive  nerve  filaments  are  supplied 
to  the  muscles  as  well  as  motor  filaments,  and  that  through  these 
we  are  affected  by  the  organic  condition  of  the  tissue,  as  in  the 
first  class  of  feelings  above  described ;  but  it  does  not  follow  that 
we  obtain  by  the  same  filaments  a  distinctive  feeling  of  the  degree 
of  the  muscle's  contraction."  When,  a  few  lines  farther  on,  Bain 
speaks  of  "  a  sense  of  expended  energy"  as  "  the  great  character- 
istic of  the  muscular  consciousness,"  his  precise  view  becomes 
indistinct  and  somewhat  confused. 

Landry,  a  little  later  ('Traite  des  Paralysies,'  1859),  relying  upon 


APPENDIX.  693 

pathological  as  well  as  psychological  data,  re-affirms  the  same  kind 
of  view  as  that  of  Hamilton  (doubted  by  Bain)  in  reference  to  the 
existence  of  impressions  yielding  feelings  of  tension  coming  from 
the  muscles  by  sensory  nerves ;  only,  instead  of  regarding  (with 
Hamilton)  these  impressions  as  subsidiary,  he  deems  them  all-im- 
portant, and  denies  that  our  notions  of  resistance,  weight,  &c.,  can 
be  derived  from  any  mer^  cerebral  process,  or,  indeed,  from  any 
other  source  than  the  moving  parts  themselves.  He  says : — "  The 
ego  has  a  direct  consciousness  of  the  phenomena  of  volition;  it 
knows  immediately  that  there  has  been  a  voluntary  stimulus,  and 
to  what  part  of  the  body  it  is  directed ;  as  to  the  effects  produced 
it  is  only  mediately  informed  of  these  and  can    disregard  them 

The  nervous  action  which  incites  the  movement  can  only, 

therefore,  furnish  to  consciousness  an  idea  of  the  volition,  and  not 

that  of  its  execution It  is  necessary  that  the  effect  of 

the  central  incitation  (the  contraction)  should  be  produced  in  order 
that  the  brain  may  perceive,  and  then  it  perceives,  at  the  same 
time,  both  the  seat  and  the  degree  of  contraction.  The  movement 
itself  is,  therefore,  the  source  whence  we  derive  notions  of  this  hind." 
This  latter  part  of  the  view  of  Landry,  adverse  to  the  notions  of 
Miiller,  Hamilton,  Ludwig  and  others,  in  regard  to  the  '  locomotive 
faculty,'  was  about  the  same  time  indejDendently  affirmed  by  G.  H. 
Lewes  ('Physiol,  of  Common  Life,'  vol.  ii.  1860),  though  in  regard 
to  the  mode  in  which  we  derive  our  impressions  from  the  moving 
members,  Lewes,  in  part,  introduced  us  to  a  new  view — based  how- 
ever, upon  very  debatable  grounds.  He  deemed  it  an  error  to  reg;i  rd 
the  nerves  of  the  anterior  and  of  the  posterior  roots  as  essentially 
distinct  in  function :  the  fibres  of  each,  he  contended,  are  both  sen- 
sory and  motor — that  is  capable  of  transmitting  ingoing  impres- 
sions as  well  as  outgoing  stimulations,  though  they  may  minister 
to  these  functions  in  different  proportions.  The  kind  of  sensibility 
to  which  motor  nerves  diiectly  contribute  (by  conveying  impres- 
sions backwards  from  muscle  to  motor  centre)  must,  Lewes  thought, 
"  be  that  of  what  we  call  the  Muscular  Sense,  by  which  we  adjust 
the  manifold  niceties  of  contraction  required  in  our  movements.'* 
"The  body  is  balanced,"  he  added,  "by  an  incessant  shifting  of  the 
muscles,  one  group  antagonizing  the  other.  But  this  would  be 
impossible,  unless  each  muscle  were  adjusted  and  co-ordinated  by 
sensation."  Lewes  admits,  however,  that  such  sensations  do  not 
much  "emerge  into  that  prominence  which  causes  the  mind  to  attend 
to  them,"  and  he  cites  Schiff  as  holding  the  view  that  "  all  the  pheno- 
mena {i.e.,  conscious  impressions)  attributed  to  the  muscuiui  scnso 


694  AFPEMDIX. 

are  due  to  the  folding?  and  stretchings  of  the  sldn  when  the  mupc^ea 
contract*."     TrcKSseau'st  view  was  very  similar  to  that  of  Schiff. 

Wiuidt  ('  Menschen-u.  Thier-Seele,'  I.  p.  222,  ls63),  thinks  it 
most  probable  that  "  the  sensations  accompanying  the  contraction 
of  the  muscles  arise  in  the  nerve  fibres  that  transmit  the  motor 
impulse  from  the  brain  tc  the  muscles."  If  it  were  due  to  sensory 
nerve?  in  the  muscles,  he  says,  "  the  muscular  sensation  would 
constantly  increase  and  decrease  with  the  amount  of  internal  or 
external  work  done  by  the  muscle.  But  this  is  not  the  case;  for 
the  strength  of  the  sensation  is  dependent  only  on  the  strength  of 
the  motive  influence  passing  outwards  from  the  centre,  which  sets 
en  the  innervation  of  the  motor  nerves."  A  statement  similar  to 
this  wag  made  by  Hamilton,  though  it  has  now  been  shown  to  be 
completely  erroneous.  The  contrary  condition  of  things  is,  indeed, 
well  illustrated  by  the  cases  of  Demeaux,  and  Spaeth  (pp.  698,  700). 

Bain's  statements  in  the  second  edition  of  his  work  (1864)  become 
more  explicit  than  they  were  in  the  jBrst.  He  says: — "  Our  safest 
assumption  is  that  the  sensibility  accompanying  muscular  move- 
ment coincides  with  the  outgoing  stream  of  nervous  energy,  and 
does  not,  as  in  the  case  of  pure  sensation,  result  from  an  influence 
passing  inwards  by  ingoing  or  sensory  nerves."  This  oi)inion  is 
repeated  and  emphasized  in  the  third  edition  (1868),  in  which  he 
adds  (p.  76),  in  regard  to  the  characteristic  feeling  of  exerted 
force,  *'  we  are  bound  to  presume  that  this  is  the  concomitant 
of  the  outgoing  current  by  which  the  muscles  are  stimulated 
to  act."  He  considers  it  to  be  of  immense  consequence,  from  a 
philosophical  point  of  view,  that  such  impressions  should  be  asso- 
ciated with  the  outgoing  current,  and  not  dependent  upon  ordinary 
sensory  nerves.^] 

Bastian  ('  On  the  Muscular  Sense,'  Brit  Med.  Journ.,  April, 
1869)  says: — "All  the  evidence  we  can  obtain  from  disease,  and 
also,  as  I  think,  the  evidence  which  we  can  obtain  from  the  most 
careful  examination  of  our  own  sensations,  goes  rather  to  sup])ort,  so 
far,  the  opinion  of  Landry— that  these  impressions  do  not  depend 
upon  our  notions  of  the  quantity  of  nerve-force  liberated  during  a 
volitional  effort,  or,  in  other  words,  upon  the  mind's  ccnsciousness 

*  Sec  his  '  Muskel  u.  Nervenphysiol.,'  pp.  15G,  ff, 

t  '  (Jlinical  Medicine,'  art.  '  Locomotor  ataxy '. 

t  The  very  existence  of  sensory  nerves  in  Muscles  was  formerly  held  to  be  qiiita 
uncertain.  This  dnubt,  however,  no  longer  exists.  The  investisutions  of  Sachs 
('  (Jentralblatt  f iir  die  Med.  Wisseiisch.,'  187.S,  and  '  Aichiv  filr  Anatomic,'  lS74i  have 
shown  conclusively  that  sensory  fibres  are  abninlani  within  the  Muscle  itself,  and 
that,  having  a  cour.se  aud  distribution  ciitirtly  distinct  from  the  motor  fdaments 
thny  enter  the  Spinal  Cord  by  the  po;^terior  or  sensoiy  roots  of  the  spinal  nerves. 


APPENDIX. 


695 


of  its  own  outgoing  energy."  The  feeling  of 'expended  energy ' 
by  which  we  obtain  our  ideas  of  resistance  and  of  an  external 
world  is  not  contained  in,  or  an  appanage  of,  the  volitional  act, 
**  but  is  derived,  through  impressions  emanating  from  the  moving 
organs  themselves."  Our  perceptions  of  'resistance 'and  of  'weight* 
are,  in  fact,  "  partly  made  up  of  tactile  impressions,  partly  of 
passive  sensations  emanating  from  our  muscles  and  joints,  and  of 

inferences  founded   upon   these We   experience  certain 

feelings  of  pressure,  combined  with  certain  sensations  in  the 
muscles  and  in  the  joints,  and  we  gradually  come  to  associate 
certain  combinations  of  these  with  the  sensations  produced  by 
handling  certain  standard  weights."  If  the  term  *  muscular  sense ' 
is  not  to  be  applied  to  the  passive  sensibilities  of  muscle,  then  it 
must  be  restricted  to  mere  'unconscious'  impressions,  which  may, 
perhaps,  pass  upwards  from  spmal  motor  ce^itres  to  the  brain  by  a 
special  set  of  fibres  (see  p.  699,  note).  Such  an  endowment  would, 
in  that  case,  have  to  be  regarded  as  "  an  unconscious  organic  guide 
in  the  performance  of  voluntary  movements,"  and  for  the  existence 
of  some  such  guide,  evidence  is  not  altogether  wanting.  It  would 
also,  in  all  probability,  supply  the  guiding  sensations  necessary 
during  the  continuance  of  automatic  movements. 

If  we  attempt  to  classify  the  views  (which  have  been  above  set 
forth  or  referred  to  in  mere  order  of  time),  as  to  the  modes  by  which 
we  apprehend  different  degrees  of  resistance  and  'iceight,  they  may 
be  ranged  as  follows : — 

1.  Estimation  of  Will-force  (through  a  ao-called  'loo  mo- 
tive faculty  ')  anterior  to  aud  independent  of  sensations  from 
the  moviijg  members.     Scaliger  and  Wundt. 

2.  By  a  "sense  of  expended  energy"  which  is  "a  con- 
comitant of  the  outgoing  current  "—that  is,  by  a  sensory 
revelation  resulting  from  the  activity  of  motor  centres, 
nerves  and  muscles.  (This  view,  which  is  allied  to  the  last, 
differs  from  it  by  the  added  supposition,  that  the  appreci- 
ation of  weight  ur  resistance  requires  more  than  the  activity 
of  the  volitional  centre,  and  can  take  place  only  on  con 
dition  that  the  motor  incitation  is  not  stopped  by  paralyzing 
or  o.her  lesions,  but  goes  on  to  evoke  the  activity  of  the 
motor  neives  and  muscles  with  which  the  volitional  centre 
is  in  relation.)    Bain. 

3.  By  ingoing  currents  or  impressions  from  the  muscles, 
conveyed  back  to  tbe  volitional  centres  by  the  uioror 
nerves  themselves.  (Mcording  t<j  this  view,  motor  centres 
and  n  rves  would  be  coincic  ently  or  in  immediately  succea 
give  increments  of  time  enga^-ed  with  outgoing  and  with  in 
going  c  urrenta. )     Lewes, 


Throug-h. 

Motor 
Centres. 


Througrh 
Sensory- 
Centres. 


696  APPET^DIX. 

4.  Principally    in    the    way    sijecified    by    Scaligor    (i.«„ 
.     through  a 'locomotive  faculty '),  though  this  ai)preciation  13 

J.riroug'n  I     aided  by  ordinary  sensory  impressions,  traversing  sensory 

motor  ancl       {      nerves  and  coming  from  the  moving  members,  e.g.,  by  feel- 

►-eTisory  j     jngs  of  tension  and  pres.'-ure  from  the  nius-cles  (' musicular 

W/entres.  j     souse'),  and  feeliugs  of  pressure  emanating  from  the  skin. 

/,  Milller  and  Hamilton. 

5.  Through  impressions  of  tension  and  pressure  trans- 
mitted by  ordinary  sensory  nerves  from  the  moving  mem- 
bers, e.g.,  from  muscles,  from  joints  and  from  skin  ;  and 
possibly,  in  addition,  through  certain  *  unconscious '  impres- 
sions passing  by  special  afferent  nerves  from  the  spinal 
motor  centres.     Bantiayi. 

6.  Through  impressions  of  tension  and  pressure  emanating 
from  the  coiitracting  muscles,  transmitted  by  ordinary  sen- 
sory nerves  of  muscle  to  sensory  centres.     Landry. 

7.  Through  cutaneous    and  articular  impressions  alone. 
^    Schiff  and  Trouss>  au. 

On  tlie  other  hand,  in  regard  to  the  existence  and  nature  of  any- 
thing like  a  distinct  'muscular  sense,'  we  meet  with  the  following 
different  views : — 

1.  That  there  is  such  an  Endowment:  though  opposing  notions 

are  entertained  as  to  the  source  of  its  impressions  and  as 
to  its  seat. 

a.  Its  impressions  (becoming  symbols  of  '  weight'  or 
*  resistance ')  are  derived  from  muscles  through 
sensory  nerves,  and  its  seat  is  on  the  sensory  side. 
Hamilton,  Landry,  &c. 

h.  Its  impressions  are  derived  from  muscles  through 
motor  nerves,  and  its  seat  is  on  the  motor  side. 
Leives.  (Allied  to  this,  though  each  differing 
somewhat  therefrom,  are  the  views  of  Wundt 
and  Bain.) 

2.  That  there  is  no  such  Endowment. 

a.  That  impressions  giving  notions  of  *  weight'  and 
'  resistance,'  and  knowledge  of  the  position  and 
movements  of  a  limb,  are  not  derived  from 
muscles.     Schiff  and  Trousseau. 

I.  That  the  above  impressions  are  only  in  part 
derived  from  muscles,  and,  as  those  having  such 
an  origin  are  for  the  most  part  of  the  *  uncon- 
scious '  type,  that  there  is  no  endowment  worthy 
of  the  name  of  *  muscular  sense.'     Bastian. 


APPENDIX.  no? 

Since  1869  the  principal  contributions  to  the  subject  have  been 
made  by  Bernhardt  ('  Archiv  fiir  Psyciiiatrie  ',  vol.  iii.,  1872),  Weir 
Mitchell  (' Injuries  of  Nerves',  1872),  Ferrier  ('Functions  ot  the 
Brain',  1876),  and  G.  H.  Lewes  ('Brain,'  No.  i.,  April,  1878). 

Bernhardt  supports  the  intermediate  view  that  our  notions  of 
*  resistance '  and  'weight'  are  derived  principally  from  an  appre- 
hension of  the  degree  of  outgoing  energy  in  the  volitional  centre, 
though  in  part,  also,  from  ordinary  centripetal  impressions.  Weir 
Mitchell  also  holds  an  intermediate  doctrine:  he  admits  the  efficacy 
of  ordinary  centripetal  impressions  from  skin,  joints,  and  muscle, 
though  he,  in  addition,  relies  upon  an  estimation  of  another  kind, 
more  distinctly  connected  with  the  volitional  act,  either  in  the 
manner  suggested  by  Scaliger  and  Wundt,  or  else  after  the  fashion 
suggested  by  the  present  writer  in  1869.  His  words  are  {loc.  cit. 
p.  358): — "Probably,  then,  a  part  of  those  ideas  which  we  are  pre- 
sumed to  obtain  through  the  muscular  sense  are  really  coincident 
with,  and  necessitated  by,  the  originative  act  of  will,  or  else  are 
messages  sent  to  the  sensorium  from  the  spinal  ganglia  which  every 
act  of  motor  volition  excites."  Weir  Mitchell  adduces  many 
extremely  interesting  facts  in  reference  to  the  sensations  in  ques- 
tion, and  the  power  of  recalling  feelings  of  movement  referred  to 
amputated  limbs,  which  have  a  very  interesting  bearing  upon  this 
subject.  He  thinks,  and  his  facts  seem  to  show,  that  something 
more  than  mere  ordinary  centripetal  impressions  require  to  be 
postulated;  but  he  admits  that  these  facts  may  be  explained  just 
as  well  by  impressions  passing  to  the  sensorium  from  spinal  as 
from  cerebral  motor  centres.  So  far,  therefore.  Weir  Mitchell's 
views  are  closely  in  accord  with  those  previously  expressed  by 
the  writer  in  1869 — though  this  was  apparently  unknown  to 
Mitchell  at  the  time  of  the  publication  of  his  work. 

The  reasons  cited  by  the  present  writer  in  1869  seemed  quite 
sufficient  to  entitle  him  absolutely  to  reject  the  notion  that  degrees 
of  'resistance'  and  'weight'  were  apprehended  through  the  cerebral 
motor  centres,  rather  than  from  centripetal  impressions.  The 
grounds  for  this  rejection  have  been,  however,  very  decidedly 
strengthened  by  Ferrier.  Experiments  made  by  himself  and 
Lauder-Brunton  show  that  muscular  discrimination  of  weight  is 
independent  of  the  volitional  act,  since  it  can  be  exercised  when 
the  muscles  are  made  to  contract  artificially  by  means  of  the 
electric  stimulus  {loc.  cit.,  p.  228).  The  facts  furnished  by  certain 
persons  suffering  from  complete  Heml-anoesthesia  also  seem  con- 


698  APPENDIX. 

clusively  opposed  to  the  notion  of  Wundt,  Bain  and  Lewes,  and  to 
others  who  may  hold  that  any  part  of  our  notions  concerning 
degrees  of  '  resistance '  are  derived  from  the  volitional  or  motor 
centres.  A  case  of  this  kind  was  long  ago  recorded  by  Demeaux*". 
some  details  of  which  are  well  worthy  of  being  cited.  There  was 
a  complete  loss  of  sensibility  (both  superficial  and  deep)  ia 
the  moving  member,  and  Demeaux  says: — "She  put  her  muscles 
in  action  under  the  influence  of  her  will,  but  she  had  no  con- 
sciousness of  the  movements  which  she  executed ;  she  knew  not 
what  was  the  position  of  her  arm — it  was  impossible  for  her  to  say 
whether  it  was  extended  or  flexed.  If  one  told  the  patient  to  raise 
her  hand  to  her  ear,  she  executed  the  movement  immediately;  but 
when  my  hand  was  interposed  between  her  own  and  the  ear,  she 
was  not  conscious  of  it ;  if  I  stopped  her  arm  in  the  midst  of  its 
movement,  she  did  not  become  aware  of  it.  If  I  fixed,  without 
allowing  her  to  be  aware  of  it,  her  arm  upon  the  bed  and  told  her 
to  raise  the  hand  to  her  head,  she  strove  for  an  instant  and  then 
became  quiet,  believing  that  she  had  executed  the  movement.  If 
I  induced  her  to  try  again,  showing  her  that  her  arm  had  remained  in 
the  same  place,  she  attempted  to  do  so  with  more  energy,  and  as 
soon  as  she  was  compelled  to  call  into  play  the  muscles  of  the 
opposite  side  [of  the  body],  she  recognized  that  the  movement  was 
opposed." 

In  the  recent  contribution  of  G.  H.  Lewes  to  this  subject,  he 
brings  forward  no  new  arguments  against  the  possible  exclusive 
adequacy  of  passive  sensibilities,  and  he  now  largely  admits  them 
as  components  of  the  complex  group  of  impressions  resuliinq  from 
movements  which  go  to  make  up  what  is  known  as  the  'Muscular 
Sense.'  And  except  that  he  holds  to  the  doctrine  that  some  active 
sensibilities  enter  into  the  same  complex,  his  present  views  are 
almost  entirely  in  accordance  with  those  expressed  by  the  writer,  in 
the  paper  above  referred  to.  The  evidence  which  Lewes  considers 
favourable  to  the  existence  of  an  '  active '  element  in  the  '  muscular 
sense'  endowment,  can,  in  the  writer's  opinion,  be  better  explained 
by  the  supposition  previously  started,  and  still  favoured  by  him, 
that  a  set  of  *  unfelt '  impressions  relating  to  states  of  tension  of 
muscles  exists— the  components  of  which  are  more  or  less  distinct 
from  those  that  revoal  themselves  in  consciousness. 

The  writer,  for  instance,  pointed  out  in  1869  that  in  '  locomotor 

*  'Dcs  Ilernics  Crurales,"  Thfese  de  Paris,  1843,  p.  100,  and  quoted  by  Ferrier  in  his 
Functions  of  the  Brain,'  "d  181. 


APPENDIX.  699 

ataxy'  the  amount  of  svmi)toms  indicative  of  a  diminution  in  the 
Bo-called  'muscular  sense'  was  generally  proportionate  to  the  im- 
pairment ot  the  different  modes  of  common  sensibility  in  the  limb. 
Yet  some  more  exceptional  cases  of  this  disease  recorded  by 
Bazire,  Trousseau  and  others,  as  well  as  some  remarkable  cases 
referred  to  by  Landry,  in  which,  without  the  existence  oj  anoesthesia, 
the  patients  were  reduced  to  a  condition  very  similar,  as  regards 
motility  and  the  sensations  resulting  from  movement,  to  that  of 
Demeaux's  patient,  seemed  to  show  pretty  conclusively  "that  the 
brain  is  assisted  in  the  execution  of  voluntary  movements  by  guid- 
ing impressions  of  some  kind,  which,  whilst  they  differ  in  mode  of 
origin  from  the  impressions  derivable  by  means  of  the  ordinary 
cutaneous  and  deep  sensibility,  may  differ  still  further  from  these, 
owing  to  the  fact  of  their  not  being  revealed  in  consciousness*  .  .  .  . 
There  is  clearly  a  loss  of  something  in  these  cases,  of  a  something 
v^hich  serves  as  a  guide  in  the  execution  of  voluntary  movements, 
but  whose  absence  can  be  compensated  by  the  supervision  of  the 
visual  sense ;  and  this  is  in  great  part  the  function  which  some 

physiologists  attach  to  the 'muscular  sense' my  position 

is  that  these  impressions  of  the  muscular  sense,  whose  existence 
we  are  thus  obliged  to  postulate,  are  unconscious  impressions, 
and  that  the  conscious  impressions  that  have  usually  been  stated 
to  fall  within  its  province  are  really  derivable  through  modes  of 
ordinary  cutaneous  and  deep  sensibility." 

The  conclusions  thus  deduced  in  1869,  are  fully  borne  out  by 
what  we  now  know  concerning  Hemi- anaesthesia  of  cerebral  origin. 
The  instance  recorded  by  Demeaux  is  altogether  exceptional,  since 
in  many  of  such  cases  complete  superficial,  and  in  some  even  deep 

*  The  route  of  these  afferent  impressions  at  the  commencement  and  towards 
the  end  of  their  course  was  then  wholly  unknown.  And  in  face  of  difficulties 
presented  by  evidence  adduced  by  Arnold,  the  writer  hazarded  the  following 
conjecture  :  "  Thus  I  assume  it  to  be  possible  that  when  molecular  changes  are 
excited  in  certain  spinal  motor  cells  as  a  result  of  a  volitional  impulse,  proportional 
recurrent  impressions  may  be  carried  along  certain  fibres  taking  origin  from  the 
motdr  cells,  and  ascending  in  the  posterior  columns  of  the  cord."  In  this  way 
the  brain  might  derive  impressions  referrible  to  the  degree  of  activity  of  the 
various  muscles,  or  sets  of  muscles,  of  a  limb.  But  our  present  increased  knowledge 
concerning  the  existence  of  'sensory'  nerves  in  muscle,  no  longer  renders  neces-sary 
any  such  hypothesis,  especially  as  the  writer  is  now  inclined  to  agree  with  Ferrier 
in  his  interpretation  ('  Functions  of  the  Brain,'  p.  ^20)  of  Aincjld's  experime'its.  Be 
thus  no  longer  feels  any  difficulty  in  believing  that  some  of  the  sensory  fibres  of 
muscles  which  enter  the  spinal  cord  by  the  posterior  roots  of  the  spinal  nerves,  may 
transmit  to  the  brain  those  almost  ever-pres-nt  '  unconscious.' impressions  which 
■o  mati  lially  guide  us  in  ihe  execution  of  all  our  muvemeiits. 


700  APPENDIX. 

and  superficial,  anasstliesia,  may  exist  without  much  if  at  all  dh' 
turbing  the  co-ordination  of  movements  on  the  same  side  of  the  body 
— a  phenomenon  several  times  seen  by  the  writer,  and  which  was  also 
recently  pointed  out  to  him  by  Prof.  Charcot  on  the  occasion  of  an 
examination  of  some  of  his  remarkable  hemian^esthetic  2:)atients  at 
la  Salpetriere.  In  Demeaux's  case  (in  addition  to  cutaneous  and 
deep  sensibility)  those  peculiar  'unconscious'  impressions  may 
have  been  cut  off,  the  loss  of  which  alone  in  the  patients  of  Landry 
produced  an  inco-ordination  of  movement  in  the  absence  of  sight 
impressions.  His  case  is,  therefore,  most  instructive  in  its  bear- 
ings upon  the  general  question.  There  was  in  this  woman  a  total 
disappearance  of  all  that  kind  of  knowledge  which  has,  by  one  or 
other,  been  ascribed  to,  or  supposed  to  be  derived  from,  the  *  mus- 
cular sense.'  The  woman  was  ignorant  of  the  position  of  her 
limbs,  and  unconscious  of  any  movements  which  she  might  execute. 
The  volitional  centres,  the  spinal  motor  centres,  the  motor  nerves 
and  the  muscles  were  capable  of  being  called  into  activity  as  before 
— yet  all  the  information  usually  supposed  to  be  derived  through 
the  '  muscular  sense  '  had  vanished. 

A  preci.-icly  similar  condition  of  things  also  existed  in  a  cele- 
brated case  of  spinal-cord  disease,  associated  with  extreme  anaesthe- 
sia, which  was  observed  by  Spaeth  and  Schueppel  (see  Ziemssen's 
"  Cyclopaedia,"  vol.  xiii.  p.  88).  Concerning  the  state  of  this 
patient  the  following  note  may  be  quoted: — '•  Sense  of  pressure  in 
the  upper  extremity,  and  the  sense  of  force,  entirely  extinct.  Sense 
of  position  of  the  upper  extremity  and  of  passive  movements  of 
the  latter  completely  extinct.  Movements  of  the  upper  extremities 
powerful  and  perfectly  correct;  the  patient  eats  alone,  dresses  him- 
self, etc.,  as  far  as  he  can  direct  his  acts  with  his  sight" 

No  clearer  evidence  than  this,  together  with  what  has  been 
previously  mentioned,  could  be  forthcoming  to  show  that  the  know- 
ledge of  the  position  of  our  limbs,  of  their  movements,  and  of  the 
state  and  degrees  of  contraction  of  our  muscles  generally,  does 
not  depend,  as  Wundt,  Bain,  and  others  assume,  upon  impres- 
sions that  are  "concomitants  of,"  or  that  coincide  with,  "the 
outgoing  stream  of  uervous  energy.** 


INDEX. 


Action,  intellectual,  basis  of,  183. 
Agouti,  brain  of,  257. 
Agraphia,  instances  of,  659-664. 

,,  nature  of,  657. 

,,         seat  of  lesion  in,  686. 


,,         life  activity  of,  8. 
Amnesia,  incoordinate,  634. 

„         illustrations  of,  619-647. 

„         mode  of  investigation  of,  682. 

„         seat  of  lesion  in,  1 82,  685. 

„         varieties  of,  620. 

„         verbale,  nature  of,  619. 
Amphibia,  brain  of,  119. 
Anatomists,  early,  on  brain,  513. 
Ancients,   vievrs  of,    concerning  brain, 

511. 
Animal  units,  7. 

Anterior  Commissure,  128,  133,  271,  454 
Apes,  intelligence  of,  321-331. 

,,      man  like,  brains  of,  295-306. 
Aphasia,  647. 

„        instances  of,  649-657. 

„        seat  of  lesion  in,  675,  684,  686. 

,.        varieties  of,  687. 
Aphemia,  instances  of,  665-672. 

„         nature  of,  664. 

„         se«-t  of  lesion  in,  686. 
Appetites,  222. 
Area  of  consciousness,  501. 
Arrest  of  development  of  Cerebral  Hemi- 
sphere, 393. 
Arthi'opods,  nervous  system  of,  101. 
Ascending  frontal  Convolution,  447. 
Association,  doctrine  of,  175. 

,,  system  of  fibres,  452. 

Asymmetry  of  Hemispheres,  400. 
Atiophy  of  one  cerebral  Hemisphere,  493. 
„        unilateral,  of  Cerebellum,  507. 


Auditory  nerve,  relations  of,  470,  506. 

,,         saccules,  85. 

„         word-centres,  diminished  ex 
citability  of,  621,  627. 
Automatic  movements,  deferred,  561. 


Baboon,  brain  of,  294. 
Base  of  brain,  471. 
Bat,  brain  of,  265. 
Beavers,  intelligence  of,  311. 
Beetle,  brain  of,  103. 
13end  of  the  stream,  .586. 
Bilateral  movements,  496. 
Birds,  brain  of,  134. 

„      cerebellum  of,  131. 
„      cerebral  lobes  of,  132. 
„      instincts  of,  246. 
„      medulla  of,  130. 
„      mental  pov^^ers  of,  246,  252. 
„      optic  lobes  of,  131, 
„      third  ventricle  of,  128. 
Blov5^-fly,  brain  of,  104.  * 

Boa-Constrictor,  brain  of,  126.,- 
Brachiopods,  nervous  system  of,  72. 
Brain,  base  of,  471. 

,,     comparative  weight  of,  in  birds 

and  mammals,  V52. 
„    fissures  of,  380,  386. 
„    heaviest  human,  368. 
„    human,  convolutions  of,  381-410t 
,,    hiiman,  structure  of,  428-476. 
,,     origin  of,  64. 
Brain  of  Agouti,  257. 
,,        Amphibia,  119. 
„        Baboon,  294. 
„         Bat,  265. 
„        Beetle,  103. 
„        Birds,  134. 
„         Blow-fly,  104. 
„        Boa-Constrictor,  12(J. 


702 


INDEX 


of  Bushwoman,  379-386. 
Calt,  268. 
Carp,  117. 
Cat,  268,  283. 
Chelonian,  268. 
Chimpanzee,  296. 
Chinese,  359,  373. 
Coati,  283. 
Cod,  122. 
Coney,  280,  281. 
De  Morgan,  390,  397. 
Dog,  270,  283. 
Dolphin,  262,  269,  284. 
Epileptics,  364. 
Fox,  283. 
Gauss,  287,  392. 
Gibbon,  289. 
Giraffe,  280,  281. 
Gorilla,  208,  301. 
Hare,  263. 
Horse,  256,  258. 
Hottentot  Venus,  377. 
Howler  Monfcey,  290. 
Human  Foetus,  289,  332,  346. 
Idiot,  297. 

Invertebrates,  107-110. 
Journalist,  390,  394. 
Kangaroo,  255. 
Lemur,  289. 
Lizard,  127. 
Macaque,  287,  289. 
Manj:abey,  291,  292. 
Manlike  Apes,  295-306. 
Marmoset,  289. 
Orang,  299,  300,  302. 
Perch,  113,  116,  128. 
Pil^e,  114. 
,        Dcrpoise,  264. 
,        Quadrumana,  286. 
,        Quadrupeds,  254. 
,        Rabbit,  261. 
,        Ray,  117. 
,        Reptiles,  125. 
,        Roach,  115. 

Scotchman,  382. 
Shark,  115. 
Squirrel,  206. 
Squirrel-Monkey,  289. 
Wanderoo,  293. 
weight  of  and  Intelligence,  370, 
375. 
Brain-weights  of  distinguished  men,  369- 
372. 
f,  „  Insiine,  363. 


Brain-weights  of  negi'oes,  358. 

,,         ,,  vertebrates,  ISO. 

Bushwoman,  brain  oi,  379-383. 


Calf,  brain  of,  268, 
Carp,  „  117. 
Cat,  „        269,  28S. 

Centipede,  nervous  system  of,  95. 
Central  lobe,  341. 

Centres,  convolutional,  for  Hearing,  534. 
Sight,  533. 
„  „  Smell,  535. 

„  „  Taste,  537. 

„  ,,  Touch,  538. 

,,        for  perception,  525,  544. 
Cerebelkim  and  Sexual  Instinct,  500. 

,,  Voluntary    Movements, 

502,  506. 
„  cortex  of,  465. 

„         functions  of,  407,  510,  508. 
„  hviman,  404. 

„  of  Birds,  131. 

„  Cat,  265. 

„  Dog,  265. 

„  Fishes,  112,  114. 

„  Mammals,  262. 

„         Peduncles  of,  460. 
„  „  upper,  401,  503, 

505. 
„  „  middle,       464, 

5^6. 
„  „  lower,  462,  503, 

505. 
„         supposed  sensory  functions 

of,  504. 
,,         imilateral  atrophy  of,  507. 
Cerebral  Cortex,  functions  of,  585. 
,,  ,,        stimulation  of,  570. 

„       Hemispheres,  effects  of  rem<:*val 

of,  577. 
„  ,,  functional    rela- 

tions of,  483. 
„  ,,  ofmammals,2C5- 

285. 
„  Lobes  of  Birds,  132. 
„  ,,  Fishes,  112,  llT. 

„  ,,  Reptiles,  127. 

„        localization,  674. 
„       Mental  Substrata,  287,  600. 
„        Peduncles,  430,  444. 
,,        Systemic  Nerves,  472. 
Cerebration,  Unconscious,  144. 


INDEX. 


703 


Cerebrum,  localization  of  functions  in, 

520-547;  570,  673. 
Chelonian,  brain  ot,  268. 
Chimpanzee,  brain  ot,  296. 

,,  intelligence  of,  325,  330. 

Chinese,  brain- weight  ot,  359,  373. 
Chiton,  nervous  system  ot,  79. 
Civilization  and  size  ot  Brain,  351,  374. 
Classification,  organic,   ot   Impressions, 

165. 
Coati,  brain  oi,  283. 
Coa,  brain  ot,  122. 
Cognitions,  unconscious,  163,  169. 
Commissures,  anterior,  128,  133,  271,  454. 
„  audito-visual,  damage  to, 

640-647. 
„  longitudinal,  457. 

„  middle,  272. 

„  posterior,  128,  272. 

Compassion  in  Ants,  242. 
Cunii)onents  of  mind,  636. 
Concepts,  formation  of,  417,  419. 
Coney,  brain  of,  280,  281. 
Confervse,  6. 
Conscience,  416. 
Consciousness,  143,  147. 

,,  area  of,  501. 

„  double,  491. 

„  genesis  of,  142,  195  688. 

„  in  lower  animals,  195,  219. 

„  origin  of,  195,  198,  688. 

.,  revelations  of,  139. 

„  sensorial    activity,    and, 

485. 
,,  unification  of,  490. 

Convolutional  patterns,  279. 

,,        longitudinal,  282, 
,,  ,,        oblique,  280. 

Convolutions,  Anatomy  of,  444,  451. 
„  and  Intelligence,  277. 

„  complicacy  of,  407,  410. 

„  embryonic   sti'iicture    of, 

346. 
„  in  lower   animals,   struc- 

ture of,  451. 
„  in  Quadrupeds,  276. 

„  inter-relations  of,  458. 

,,  of  Human  Brain,  3S0,  386. 

Cornu  Ammonis,  451. 
Corona  radiata,  436. 
Corpora  Albicantia,  273. 
Corpus  Callosum,  256,  273,  304,  453. 
„  „  defective,  484. 

If  I.         in  Birds,  133. 


Corpus  Striatum.  12V,  268,  437. 

„  „  functions  ot,  567. 

„  „  in  Birds,  133. 

,,  ,,  lett,  disease  of,  678. 

,,      trapezoideum,  261. 
Cortex,  excitable  area  ot.  573,  575. 

,,       ot  Cerebellum,  structure  of,  465. 

,,       supposed  motor  centres  ot,  573, 
577,  582. 
Crab,  nervous  system  of,  97. 
Cranial  capacities,  347-353. 

,,       nerves,  120. 

,,  ,,       ot  Reptiles.  129. 

Cross-relation  between  halves  of  brain 

and  body,  478,  482. 
Crura  Cerebri,  132. 
Cuttle-fish,  nervous  system  of,  Si. 


D. 

Decussation  of  optic  nerves,  115,  469. 

,,  ,,  ,,        in  Fishes,  480. 

Defects  of  Speech,  importance  of,  673. 
Degradation    of   mind    and  damage  to 

occipital  lobes,  546,  687. 
De  Morgan,  brain  of,  390,  397. 
Development  of  occipital  lobe,  397,  399. 
Diffuse  localization,  522. 
Digestion,  rudimentary,  9. 
Direction,  sense  of,  65,  214,  219,  239. 
Disease,  extensive  of  one  cerebral  Hemi- 
sphere, 493. 

,,        mental  defects  from,  611. 
Distinguished  men,  brain-weights  of,  369, 

372. 
Doctrine  of  Association,  175. 
Dog,  brain  of,  270,  283. 
„     cerebellum  of,  265. 
„    intelligence  of,  312,  315. 
Dolphin,  brain  of,  262,  269,  284. 

,,        intelligence  of,  318. 
Dxira  Mater,  384. 


Echo  sign,  626. 

Elephant,  hemisphere  of,  282. 

,,  intelligence  of,  319,  821. 

Emotion  in  Reptiles,  247. 

,,        sensorial  origin  of,  184. 
Emotional  stimuli,  paths  of,  SsOt 


704 


INDEX. 


Eolis,  nervous  system  of,  49 
Epheuieroniorphs,  4. 
Epileptics,  brain-weights  of,  364. 
External  Caiasule,  440. 


F. 

Feelings  and  relations,  636. 

,,         as  agents,  CS9. 
Fishes,  cerebellum  of,  112,  114. 

„      cerebral  lobes  of,  112,  117. 

„      medulla  of,  122. 

„      olfactory  lobes  of,  118. 

„      optic  lubes  of,  115. 

„       spinal  cord  of,  113. 
Fissure,  external  perpendicular,  299. 

,,        of  Rolando,  29S,  344. 
Fissures  of  Brain,  3S0,  386. 

,,  ,,         first  appearance  of,  341. 

,,       sylvian,  length  of,  395. 
My,  nervous  system  of,  105. 
Fornix,  256,  272,  444,  456. 
Fourth  Ventricle,  ISO,  264. 
Fox,  brain  of,  283. 
„    intelligence  of,  315. 


Ganglia  on  nerves  of  Medulla,  123. 
Ganglion,  nervous,  27. 
Gauss,  brain  of,  287,  392. 
General  Notions,  417. 

,,  ,,  formation  of,  419. 

Genesis  of  Consciousness,  142,  195,  688. 
Giant  Cell,  447. 
Gibbon,  brain  of,  289. 
Giraffe,        „  280,  281. 

Gorilla,        „         298,  301. 

,,       Intelligence  of,  327. 
Grasshopper,  nervous  system  of,  51. 
Grey  Matter,  28,  403. 

„         ,,        of  cerebellum,  465. 
Groove,  occipital,  400. 
Growth  of  Mind,  191-194. 


Habits,  inherited,  188,  211,  225,  229. 

Hare,  brain  of,  263. 

Hearing,  convolutior  al  .!ontre  for,  534. 


Hearing  in  Fishes,  organ  of,  123. 

,,  sense  of,  04,  205. 

Hemianajsthesia,  487,  494,  097. 
Hemispheres,  arrest  of  development  In, 
393. 
„  asymmetry  of,  640. 

„  atrophy  of,  493. 

„  of  Elephant,  282. 

„  Horse,  28". 

„  Rhinoceros,  280. 

Hereditary  transmission,  187. 
Heredity,  193,  224. 
Hippocampus,  450. 

,,  major,  268. 

,,  minor,  304. 

,,  relations  of,  443. 

Horse,  brain  of,  256,  258. 

,,       hemisphere  of,  280. 
Hottentot-Venus,  brain  of,  377. 
Howler-Monkey,        „  290. 

Human  foetus,  „  2S9,  332, 3431 

,,        structure  of  brain,    28,  476. 
Hypoaria,  117. 


Ideal  movements,  597,  599. 

Idiot,  brain  of,  297. 

Impressions,  classing  of,  165. 

Incoordinate  amnesia,  634. 

Inheritance,  224. 

Inherited  acquisitions,  164,  187,  183. 

,,         habits,  225. 
Insane,  brain-weights  of,  363. 
Insects,  nervous  sj'stem  of,  103. 
,,       visceral  nerves  of,  106. 
Instinct,  220-235. 

,,         classes  of,  227,  230. 

plasticity  of,  231-235. 
Instinctive  acts,  simple,  236. 

,,  operations,  188-191. 

Intellect,  derivation  of,  424. 
Intellectual  action,  basis  of,  183. 

,,  processes,  localization  of,68J 

Intelligence  and  brain-weight,  370,  37.''. 

„  gi-ades  of,  425. 

„  of  animals,  423. 

„  Apes,  323,  331. 

„  Beavers,  311. 

„  Chimpanzee,  325,  330t 

„  Dog,  312,  315. 

„  Dolphin,  318. 

i.  Elephant,  319,  321 


INDEX. 


705 


Intelligence  of  Fox,  315. 

„  Gorilla,  327. 

„  Orang,  328. 

„  Porpoise,  316. 

„  Social  Insects,  237,  246. 

,,  unconscious,  167. 

Intelligent  actions,  25. 
Internal  Capsule,  440,  487,  494. 
Internuncial  fibres,  504. 
Invertebrates,  brain  of,  i07,  110. 
Island  of  Reil,  341. 


Journalist,  brain  of,  390,  394. 
Julus,  nervous  system  of,  94. 


Kangaroo,  brain  of,  255. 
Kinffisthesis,  543,  591,  600. 
Kinaesthetic  centres,  inequality  of,  593. 
,,  impressions,  554. 

„  „  of   speech  and 

writing,  595. 
,  ff  revivability  of, 

611. 
„  „  unconscious, 

699. 
,j  word-centres,  activity  of,646. 

„  „  nature        and 

functions  of, 
617,  646. 


Language,  196,  411,  602. 

„  and  thought,  417-427,  636. 

„         as  a  developer    of    thought, 
417,  421. 

,,  development  of,  413. 

„  influence  of,  411. 

,,  in  lower  animals,  197. 

„  of  social  insects,  245. 

,,  uses  of,  412. 

Lateral  ventricles,  133. 
Leech,  nervous  system  of,  89. 
Left  Corp  p.  3  striatum,  disease  of,  678. 
„    hemisphere     and    speech      move- 
ments, 681. 
Lemur,  brain  of,  289. 
Lesion,  seat  of,  in  Amnesia,  682,  685. 


Lesion,  seat  of,  in  Aphasia,  675,  685. 

„  „  speech  defects,  G8S1 

Life  processes  of  vegetals,  2. 
Limpet,  nervous  system  of,  78. 
Lizard,  brain  of,  127. 
Lobule,  supramarginal,  303. 
Localization,  cerebral,  673-688. 

„  diffuse,  522. 

„  of  functions  in  cerebmim, 

620-547. 

„  of  intellectual     processes, 

688. 

„  topographical,  522. 

Locomotive  faculty,  692. 
Locomotor  ataxy,  699. 

,,  instinct,  553. 

Longitudinal  commissures,  457. 
Lower  animals,  consciousness  of,  195-219 
Lyra,  273. 


M. 


JIacaque,  brain  of,  287,  289. 

Mammals,  cerebral  hemispheres  of,  265- 

2S5. 
Mangabey,  brain  of,  291,  292. 
Manlike  apes,  brain  of,  295-:  06. 
Marmoset,  brain  of,  289. 
Medulla,  decussation  of  fibres  in,  433. 
„        ganglia  on  nerves  of,  123. 
„        of  Birds,  130. 
„  Fishes,  122. 

Medusae,  18. 
Megalocephaly,  362. 
Membranes  of  brain,  348. 
Memory  in  Ants,  244. 
Mental  defects  from  cerebral  disease,  618. 

,,       phenomena,  145. 

,,       processes,  different  aspects    of-, 
185. 
Micro  r^ephaly,  362. 
Middle  commissure,  272,  455. 
Mind  and  consciousness,  148. 

,,     as  an  entity,  142. 

„     cerebral  substrata  of,  589-600. 

„     comjjonents  of,  636. 

„    growth  of,  191-194. 

„    nature  of,  138-146,  150. 

„     organ  of,  151,  154,  495. 

,,     science  of,  155, 

,,     sphere  of,  495. 
Mollusks,  sense  organs  of,  75. 
Monkeys,  intelligence  of,  322, 


706 


INDEX. 


Moral  sense,  416,  426. 
Motor  activity  and  size  of  cerebrum,  278. 
„     intuitions,  354. 
,,      nerves  as  carriers  of  sensory  im- 
pressions, 693. 
Moulds,  6. 

Movement,  conception  of,  552. 
„  inciters  of,  549. 

,,  sense  of.  543, 

Movements  as  modifiers  of  sensadon,  598. 
„  bilateral,  496. 

„  classification  of,  563. 

„  defeired  automatic,  561. 

„  nervous  mechanisms  for,  558. 

„  new,  learning  of,  555. 

,;  of  plants,  15. 

,j  responsive,  23. 

,,  spontaneous,  24. 

,,  unilateral,  496. 

Muscle,  origin  of,  20. 
Muscular  consciousness,  692. 

„         sense,  69,  541,  691,  700. 

„  „       absence  of,  699. 

„  ,,       centre,  583. 

„  „       impressions  and  motor 

nerves,  693. 
„  ,,       whether  real  or  not,  696. 

,,  tensions,  appreciation  of,  092. 

Mussel,  nervous  system  of,  74. 


N. 

Nautilus,  nervous  system  of,  81. 
Negi'oes,  brain-weight  of,  358. 
Neuierteans,  nervous  system  of,  87. 
Nerve  actions,  unconscious,  145,  200-203. 
„      cells,  22,  35-38. 

„         „     relations     of,    with    nerve- 
fibres,  40-48. 
„      fibres,  30-35,  40-48. 
„  „      origin  of,  21. 

,,      tissues,  fundamental  arrangement 
of,  26. 
Nerves,  cranial,  120. 
Nui-vous  centres  of  Vertebrates,  111. 
„       system,  initiation  of,  19. 
„  ,,        of  Arthropods,  101. 

,,  „  Brachiojiods,  72. 

„  „  Centipede,  95. 

„  „  Chiton,  79. 

„  „  Crab,  97. 

„  ,,  Cuttle-fish,  84. 

„  „  Eolis,  49. 


Nervous  system  of  Fly,  105. 

„  „  Grasshopper,  51. 

„  „  Insects,  103. 

„  „  Julus,  94. 

„  „  Leech,  89. 

„  „  Limpet,  78 

,,  „  Mussel,  74. 

„  „  Nautilus,  81. 

„  „  Nemerteans,  87. 

„  „  Oyster,  73. 

„  „  Privet    hawk-mothj 

102. 

„  „  Pteropoda,  77. 

,,  ,,  Sandhopper,  96. 

„  „  Snail,  79. 

Spider,  90. 

„  ,,  Tunicata,  71. 

„  „  Water-beetle,  105. 

„  „  White  ant,  105. 

,,  ,,         visceral,  134. 

Nervi  transversi,  1U6. 
Neuroglia,  38,  139. 


Objective  psychology,  139,  141,  168. 
Occipital  groove,  400. 

„        lobe,  development  of,  397,  399. 
„        lobes  and  mental  degraJ^tion, 
687. 
Olfactory  channels,  non-decussatioa  of, 
482. 
„  lobes,  267. 

„  ,,      of  Birds,  134. 

„  ,,  Fishes,  118. 

Reptiles,  129. 
,,  tracts,  4GS. 

Optic  lobes,  264. 

„       of  Birds,  131. 
,,  ,,  Fishes,  115. 

„  „  Reptiles,  125. 

„      nerves,  decussation  of,  115,  46?    • 
„      thalanms,  269. 
,,      tracts,  408. 
Orang,  brain  of,  299,  300,  302. 

„      intelUgence  of,  328. 
Order  of  sensations,  174. 
Organ  of  hearing,  123. 
Origin  of  Consciousness,  195,  198,  688, 

,,         Nervous  System,  14. 
Outgoing  Currents,  concomitant  of,  S94. 

,,  Stimuli,  593. 

Oyster,  nervous  system  of,  73. 


INDEX. 


707 


Peduncles,  cerebral,  fibres  of,  430,  444. 
„  of  cerebellum,  460. 

„  „  lower,  462, 503, 

505 
„  „  middle,      404, 

506. 
„  „  upper,  461, 503, 

505. 
Perceptions,  177,  180,  589. 
Perceptive  centres,  523,  525-544,  590. 

„  „        modes  of  excitation 

of,  616. 
Perch,  brain  of,  113,  116,  128. 
Phrenologists,  early,  514,  517. 
Phrenology,  517,  520. 
Pike,  brain  of,  114. 
Pineal  body,  127,  271. 
Pneumogastric  nerves,  121,  135,  473. 
Pons  Varolii,  255. 
Porpoise,  brain  of,  264. 

„         intelligence  of,  316. 
Posterior  commissures,  128,  272,  456. 
Privet  Havirk-Moth,  nervous  system  of, 

102. 
Psalterial  fibres,  273. 
Psycnology,  objective,  139, 141, 168. 

,,  subjective,  139. 

Pteropoda,  nervous  system  of,  77. 
Pyriform  processes,  266. 


Quadrumana,  brain  of,  286. 
Quadrupeds,  brain  of,  254. 


R. 

Rabbit,  brain  of,  261. 

Ray,  brain  of,  117. 

Reading,  processes  involved  in,  609,  624, 

G40. 
Referred  sensations,  697. 
Reflex  actions,  25,  156-162. 

,,      movements,  516. 
Reptiles,  brain  of,  125. 

„        cerebral  lobes  of,  127. 

„        cranial  nerves  of,  129. 

„        olfactory  lobes  of,  129. 

„        optic  lobes  of,  125, 


Resistance,  appreciation  of,  691. 

„  not  recognized  by  motor  ' 

tres,  698. 
Rhinoceros,  hemisphere  of,  280. 
Roach,  Drain  ot,  115. 


s. 


Saccules,  auditory,  85. 
Sandhopper,  nervous  system  of,  96. 
Scotchman  brain  of,  382. 
Sensation  and  Perception,  589. 

,,  complex  nature  ot,  180-186. 

Sensations,  170-173,  589. 

„  and  movements,  592. 

„  order  ot,  174. 

„  visceral,  69,  545. 

Sense  endowments  and  intelligence,  307- 
311. 
„  of  direction,  65,  214,  219,  239. 
„        hearing,  64,  205. 
„        movement,  543. 
„        sight,  59,  205. 
„  ,,      in  ants,  241. 

„        smell,  208,  213. 
„        space,  219. 
„        taste,  58. 
„        touch,  206. 
„    organs  of  m  dlusks,  75. 
„        „        situation  of,  62. 
Sensorial  activity  and  consciousness,  483i 
Sensory  surfaces,  66. 
Sexual  instinct  and  cerebellum,  500. 
bhark,  115. 

Sight,  perceptive  centre  of,  533. 
„     sense  of,  59,  205. 

,,        in  Ants,  241. 


SmeU,  sense  of,  208,  213. 

„      convolutional  centre  for,  535. 
„      unilateral  loss  of,  488. 
Snail,  nervous  system  of,  79. 
Social  insects,  intelligence  of,  237,  246. 

„  language  of,  245. 

Space,  sense  of,  219. 
Speech,  defects  of,  importance  of,  673. 
„        idea  of,  595. 
„        incitations,  different  tracts 

679. 
„  „  emotional,  680. 

„  modes  of  acquisition  of,  602,  609. 
„  movements  and  the  left  Hemi- 
sphere, 681. 


708 


INDEX. 


Speech,  a  primary  automatic  act,  606. 
Spider,  nervous  system  ot,  99. 
Spinal  Cord  of  Fishes,  113. 
Spontaneous  movements,  55. 
Squirrel,  brain  of,  266. 

,,        -monkey,  brain  of,  2S9. 
Stomato-gastric  system,  98. 
Subjective  states,  140 
Substrata  of  mind,  cerebral,  589-600. 
Sylvian  fissure,  895. 
Symbolism  in  Thought,  422. 
Sympathetic  gangliun,  475. 

,,  nervous  system,  134,  472. 

Sympathy,  416. 
System  of  fibres,  441. 
Systemic  nerves,  472. 


T. 


Tactile  centres,  593. 

„      sensibility,  varieties  of,  540. 
Taenia  semici  'cularis,  456. 
Tapezoid  bodies,  261. 
Taste,  convolutioual  centre  for,  537. 

„      sense  of,  58. 
Tegmentum,  436. 
Thalamus,  128,  437. 
Third  frontal  convolution,  446. 

„      ventricle  of  Birds,  128. 
Thought  and  language,  636. 
Thought-processes,  mode  of  investigation 

of,  614. 
Touch,  active,  691. 

„      convolutiunal  centre  for,  53S,  593. 

„      different  modes  of,  66. 

„      elementary  modes  of,  57. 

„      sense  of,  206. 
Transmission,  hereditary,  186. 
Tunicata,  nervous  system  of,  71. 


Unconscious  cerebration,  144. 
„  cognition,  163,  167. 

ff  intelligence,  167. 

f,  kinsesthotic      impressions, 

699. 
-  nerve  actions,  145,  200-203. 


Unification  of  consciousness,  490. 
Unilateral  atrophy  of  cerebellum,  507. 
„         movements,  496. 


Vegetal  tissues,  transmission  of  stimuli 
through,  15-17. 
„     units,  7,  11. 
Vegetals,  Life  processes  of,  2. 
Velum  interpositum,  269. 
Ventricle,  fourth,  130,  264. 

third,  128,  270. 
Ventricles,  lateral,  267,  429. 
Vertebrates,  nervous  centres  of,  111. 
„  weight  of  brain  in,  180. 

Visceral  impressions,  68,    137,   221,  476, 
545. 
„        nerves  of  insects,  106. 
„        nervous  system,  134,  472. 
„        promptings,  137. 
„        states,  226. 
„        systemic  nerves,  472. 
Visual  word-centre,  defective  action  o^ 

627,  633. 
Vtlitioa,  analysis  of,  550. 

,,        last  mental  stage  of,  551. 
Volitional  stimuli,  path  of,  565,  576. 
Voluntary  movements,  581. 

,,  „  and  cerebellum, 

502,  506. 
„  „  mode  of    execu- 

tion of,  553-557. 


w. 

Wanderoo,  brain  of,  293. 
Water-beetle,  nervous  system  of,  105. 
Weighing  brain,  methods  of,  353. 
Weight,  appreciation  of,  695. 

„       of  brain,  influences  modifying, 

354,  375. 
,,  ,,         in  Vertebrates,  130. 

White  Ant,  nervous  system  of,  105. 

,,      matter,  nervous,  28. 
Will,  495,  550-5:2. 
,,     scope  of,  54S. 
„     source  of,  569,  582,  647. 
Writing,  processes  involved  in,  609,  617, 
646-648. 


;l^ 


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APR        R  IS 


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